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Transmission Issues in 2021

15K views 67 replies 15 participants last post by  rikiduc 
#1 ·
Title: Transmission Issues in 2021

Hey all,

I've been experiencing transmission issues similar to those that others have had in the past, and am hoping for some help to understand how to diagnose and fix these problems. I've had the same issue three times in a month now:
  1. I drive the car for a while with no issues (the first time I had been driving the car for about 3 hours, the second time I had only driven it for about 30 minutes)
  2. Park the car and turn it off for a little bit (the first time this was only a few minutes as I filled up for gas. The second time the car was off for ~2 hours)
  3. When I go to restart the car I get the "Christmas Tree of death", reverse and manual mode are not available, and only 2nd, 4th, and 6th gears work. The first time this happened the car actually got stuck in reverse for a bit before it finally went into neutral, but then couldn't go back to reverse or into 1st/3rd/5th.
  4. No amount of key on/key off/reboots changes anything. If I pull the negative battery terminal AND let the car sit about 30 minutes, it will suddenly fire up just fine. All the warning lights go off except the CEL, all gears and modes are available, and the car shifts just fine. After driving for some amount of time, the CEL also clears itself.
  5. The third incident occurred while driving this morning. On the freeway with the cruise control engaged and car in auto mode, the transmission light briefly flashes, CEL illuminates, I get a bunch of warnings, but the car continues to shift fine in auto mode. Once I parked and turned it off, it now has all the same problems as in #3 when I try to restart it.
After the first occurrence, I took the car to the dealer and they could find nothing wrong. They double-checked the software was up-to-date (I even provided the number of the SW patch below) and confirmed there was nothing available. They then quoted me $9,000 to replace the transmission, so I took the car back and decided I would have to solve this myself.

To start, I've read all of these threads:

Transmission Failure
Transmission Failure Poll
Heads Up On a TRny Issue
Inconsistent Problems: “The Christmas Tree of Death”.

The problem is that the majority of the problems people had occurred early on, and dealers either solved the problem with a software patch which predates the build date of my car (I have a 2016) or they replaced the transmission. My car is out of warranty so a trans replacement "just in case" is not in the cards.

From what I can gather, these are the possible sources of the problem. Is this list complete and in which order should I troubleshoot this?
  • Clean/brush battery terminals and add dielectric grease - already tried this after the first incident, didn't solve the problem
  • New battery - I tested the battery at Autozone, they claim that it's totally fine, not even marginal on startup
  • Get the software patch that worked for others (CFC8TDW.01-00-UF14M080) - I gave this number to the dealer and they claimed everything is up to date
  • Check/refill "Robot mechanism" (shift actuator?) fluid level
  • Replace shift actuator pressure sensors with this part: Pressure sensor - Alfa Romeo TCT - SequParts
  • Replace voltage regulator for shift actuator
  • Replace hydraulic actuator p/n #68303710AA
  • Replace transmission
Also, is anyone aware of an Alfa tech or indie shop somewhere in the US who actually has experience troubleshooting and solving these issues? The tech at the local dealer had seen this problem many times on Fiat 500Ls, but said that they just R&R the transmission every time, so he didn't have any idea how to diagnose the root cause.

Any help would be appreciated, I don't feel like I can trust my new car enough to drive it anywhere until this gets sorted out.
 
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#2 ·
One big issue in attempting to fix the trans is that the DCT trans have low 'fix rates' as a product across all manufacturers. Going one level deeper on FCA products (Fiat-Chrysler) is that they tried to resolve many mechanical issues by fixing the original version (same architecture) found in other FCA products... to repeated failure and triggering the Lemon Law... which saw them ordered, by court/judge, to cease repairs and only replace them with updated units.

This was good news for those affected and chasing their tails under warranty, as repair after repair failed. There is bad news with that: Now there is no established knowledgebase or supply chain to allow repairs. The seeds of repair are barely at sprout level. For a trans used so widely, the reparability should be high. It exists, but it is primitive and limited. An actuator here or there, and lots of 'let's try this' ... which is thousands of dollars which might never avoid the cost of getting a replacement, but is just money piled on top.

They proved they are incapable of fixing them; they triggered the lemon law as a result; the courts ordered them to cease repairs, and now you are left holding the bag, because you seek repairs. Can't blame the courts, as FCA proved incapable, and there does not seem to be real hope beyond a crapshoot anywhere else.
 
#6 ·
Yeah, that's unfortunate. The car shifts fine when it's not glitching though, so I think this is a fixable issue that does not require trans replacement.

Have you asked for a transmission recalibration? Something about adjusting the kiss points of the clutches. My tech gave one to mine last year, I thought as a preventative measure, because I really couldn’t detect anything wrong with it. It did smooth out the changes in certain circumstances. These things are too clever for their own good, and ours.
I didn't ask, but when I brought it into the dealer, they suggested that they may reset the contact points once they had looked at it. It's not clear if they actually did this though.

How many miles do you have on your 4C, and have you ever tracked it? I'm at 12K on my 2016 so far zero issues but planning to have bolt tightening and other service performed soon in Atlanta. Will definitely be asking about the DCT.
I have 18K miles on mine. Never been to a track day as far as I know, although I did run an autocross with it back in February.
 
#3 ·
Have you asked for a transmission recalibration? Something about adjusting the kiss points of the clutches. My tech gave one to mine last year, I thought as a preventative measure, because I really couldn’t detect anything wrong with it. It did smooth out the changes in certain circumstances. These things are too clever for their own good, and ours.
 
#7 ·
Almost forgot that I took screenshots of the OBD codes I could read with my cheap Bluetooth OBD adapter. This is from the first time I had the issue (although it is after I pulled the neg battery cable):



And this is after this weekend's issue (again, post-reset):


It was suggested to me offline that I buy the Foxwell code reader to grab and reset anything that maybe isn't showing up with my cheap adapter. I have one on order (they are on sale on the Foxwell site right now, btw) and will post any additional codes that I can see once I have it. A quick Google on the codes above shows some possible issues related to the gear position sensor, so I may add that to the list of possible trouble areas.
 
#9 ·
All things considered.... reading all the information again... a mechanical issue should not come/go... and you're a 2016, but with right software in the TCM.

Has anyone considered replacing the Trans Control Module (TCM)? 2015-2016 TCMs could be compromised by water.
 
#11 ·
My car is also MY2016

I'm pretty sure the problem some have is because of the routing of the wire to the TCU. 100% sure water gets into the back of the connector and migrates into the connector on mine.

I plan on flipping my TCU over so the connectors are facing down.

Most of the body computers and wire harnesses I've been offered also appear to show issues with water running down the wire harness corroding connections, obviously creating a range of electrical issues.
 
#10 ·
So i had the Christmas tree lights happen once in the past. So many lights i could not keep up with them all... Freaked me out. I believe it was voltage related. Put it on the tender and never seen this again. Been a year or so. Just had my battery changed also last week. In for service but felt since it was a 2016 even thou they told me battery was fine these cars are finicky when it come to voltages.
 
#12 ·
Title: Transmission Issues in 2021

Hey all,

I've been experiencing transmission issues similar to those that others have had in the past, and am hoping for some help to understand how to diagnose and fix these problems. I've had the same issue three times in a month now:
  1. I drive the car for a while with no issues (the first time I had been driving the car for about 3 hours, the second time I had only driven it for about 30 minutes)
  2. Park the car and turn it off for a little bit (the first time this was only a few minutes as I filled up for gas. The second time the car was off for ~2 hours)
  3. When I go to restart the car I get the "Christmas Tree of death", reverse and manual mode are not available, and only 2nd, 4th, and 6th gears work. The first time this happened the car actually got stuck in reverse for a bit before it finally went into neutral, but then couldn't go back to reverse or into 1st/3rd/5th.
  4. No amount of key on/key off/reboots changes anything. If I pull the negative battery terminal AND let the car sit about 30 minutes, it will suddenly fire up just fine. All the warning lights go off except the CEL, all gears and modes are available, and the car shifts just fine. After driving for some amount of time, the CEL also clears itself.
  5. The third incident occurred while driving this morning. On the freeway with the cruise control engaged and car in auto mode, the transmission light briefly flashes, CEL illuminates, I get a bunch of warnings, but the car continues to shift fine in auto mode. Once I parked and turned it off, it now has all the same problems as in #3 when I try to restart it.
After the first occurrence, I took the car to the dealer and they could find nothing wrong. They double-checked the software was up-to-date (I even provided the number of the SW patch below) and confirmed there was nothing available. They then quoted me $9,000 to replace the transmission, so I took the car back and decided I would have to solve this myself.

To start, I've read all of these threads:

Transmission Failure
Transmission Failure Poll
Heads Up On a TRny Issue
Inconsistent Problems: “The Christmas Tree of Death”.

The problem is that the majority of the problems people had occurred early on, and dealers either solved the problem with a software patch which predates the build date of my car (I have a 2016) or they replaced the transmission. My car is out of warranty so a trans replacement "just in case" is not in the cards.

From what I can gather, these are the possible sources of the problem. Is this list complete and in which order should I troubleshoot this?
  • Clean/brush battery terminals and add dielectric grease - already tried this after the first incident, didn't solve the problem
  • New battery - I tested the battery at Autozone, they claim that it's totally fine, not even marginal on startup
  • Get the software patch that worked for others (CFC8TDW.01-00-UF14M080) - I gave this number to the dealer and they claimed everything is up to date
  • Check/refill "Robot mechanism" (shift actuator?) fluid level
  • Replace shift actuator pressure sensors with this part: Pressure sensor - Alfa Romeo TCT - SequParts
  • Replace voltage regulator for shift actuator
  • Replace hydraulic actuator p/n #68303710AA
  • Replace transmission
Also, is anyone aware of an Alfa tech or indie shop somewhere in the US who actually has experience troubleshooting and solving these issues? The tech at the local dealer had seen this problem many times on Fiat 500Ls, but said that they just R&R the transmission every time, so he didn't have any idea how to diagnose the root cause.

Any help would be appreciated, I don't feel like I can trust my new car enough to drive it anywhere until this gets sorted out.
Hi Nate,

We're sorry to hear about the various behaviors you're experiencing recently. If you ever need additional support alongside your dealership visit, our inbox is always open! Just send us a private message with more details so we can tailor our assistance to your needs.

Thanks,

Courtney
Alfa Romeo Cares
 
#15 ·
OK, a couple of updates - some good, some bad:
  1. I decided to check the battery myself and found that it was dropping to ~10.5V when cranking, so I decided to replace it with a new Duralast AGM. Unfortunately this didn't fix anything, but at least I can cross the battery off my list. I also checked the charging voltage (rock solid 14.2V between idle and 2500 RPM) and confirmed the hydraulic actuator fluid level is full, so those are also off the list.
  2. I bought the Foxwell code reader and it has been very helpful. So far I have seen multiple instances of the same code, P1C9900 "Gear position sensor 1st/3rd - signal frequency incorrect", which occurs when the transmission light flashes, either at startup or while driving.
  3. I drove the car a bit this weekend and the fault is now becoming persistent (i.e. no longer momentary), which means that the car goes into limp mode and won't come out, making it nearly undriveable. The only consistent pattern I'm seeing is that the fault only seems to occur when the car is fully warmed up, or on startup after a drive of 20+ minutes. However, I've also seen it go away after driving the car for a while (I had to limp the car home on only 2nd/4th/6th gears for about 60 miles on Saturday), so I'm not sure what to make of all this.
Given that this is the only code in the TCU when this is happening, and it's now happening with more frequency, I'm thinking I need to narrow down my search to either this 1st/3rd position sensor, the shifter selector position sensor, or the wiring harness around it. As best I can tell from reading the TCT training manual, this 1st/3rd position sensor is part of the "integrated sensor module" located on the backside of the hydraulic actuator (page 39 here). So this leads to a couple of questions:
  • Has anyone pulled off the hydraulic actuator themselves yet? I don't see a procedure for it in the eLearn manual, but I saw other threads where dealerships replaced it under warranty, so I'm assuming it can be done (and hopefully with the powertrain still in the car). Not sure if I need to plan for draining and refilling the hydraulic fluid, or if the system is self-contained.
  • Does anyone have access to a parts manual that lists this sensor module with a part number? I haven't been able to find anything online. Really hoping I don't have to replace the entire actuator (~$2100) just to get a replacement sensor module.
I just got all the parts to change the timing belt, so my plan is to start pulling it apart to do that service, and while I'm in there I will replace either the sensor module or the entire actuator, and also inspect the wiring. Hoping I can get some help on part numbers so I can get something ordered, otherwise I'm about to become the parts guy at Scottsdale AR's best friend, lol.

P.S. Another idea is to buy this hydraulic actuator from a Dodge Dart and just swap over the sensor module. Would be way cheaper than a new actuator, but seems risky until I can confirm the sensor modules are the same P/N. Any thoughts on that?
 
#22 ·
Well I'm trying to avoid just throwing (expensive) parts at the car, but to your point, a TCU is definitely cheaper than an actuator. You're also right that at this point I have no way of knowing whether the issue causing the fault is at the sensor or the TCU. Maybe if someone has a spare TCU laying around that they would let me borrow I could test that theory? :geek:

BTW, it is possible to buy the actuator separately: Clutch Hydraulic Unit Motor Mopar 68303710AA fits 16-18 Alfa Romeo 4C for sale online | eBay

I would take up Alfa Romeo Care up on their offer for help. In the background, with the details you have, they will reach out to their network to see if anyone solved a similar problem. I am a huge critic of service I receiver everywhere, but they are great and responsive.

Don't know what to say about the actuator gambit, other than Amazon has a good return policy. Maybe use it as nothing more than a test item to clear a variable? -- but I don't know about compatibility.
Yes, I agree. Been meaning to hit up @AlfaRomeoCares to see if they have any additional knowledge or could at least help me find a replacement sensor module, but haven't had a chance yet.

Were you able to rule out the wiring harness connections to the TCU (corrosion issue)?
I know that you said it wasn't likely from your ownership, but the car's past life and the heat where you live might have caused latent corrosion, just enough to cause this intermittent gremlin.

I would think this a worthwhile check before starting to disassemble parts of the transmission.
I haven't yet. My DIY timing belt change has been a disaster (see my other thread), so I'm still trying to get that sorted before I come back to this issue. Once I finish the belt (almost done) I plan to take off the driver side quarter panel so I can inspect the TCU connections, chassis ground connections, and as much of the actuator wiring harness as I can get to. Definitely doing this before I start taking the transmission apart. From what I can see, removing the actuator might be a pain. Not a lot of room to maneuver it out.

Good information.

To trigger these re-learns, they connected their system, or just disconnected the battery?

I assume the former (I think that the only transmission re-learn you can do without the diagnostic equipment is the "fine clutch adjustment", but would be happy to be corrected).
I know that my Foxwell reader has the all the transmission re-learns included in it, and it looks like there are several re-learn procedures for the ECU also. Seems like the easiest way to do it.
 
#17 ·
I would take up Alfa Romeo Care up on their offer for help. In the background, with the details you have, they will reach out to their network to see if anyone solved a similar problem. I am a huge critic of service I receiver everywhere, but they are great and responsive.

Don't know what to say about the actuator gambit, other than Amazon has a good return policy. Maybe use it as nothing more than a test item to clear a variable? -- but I don't know about compatibility.
 
#18 ·
Were you able to rule out the wiring harness connections to the TCU (corrosion issue)?
I know that you said it wasn't likely from your ownership, but the car's past life and the heat where you live might have caused latent corrosion, just enough to cause this intermittent gremlin.

I would think this a worthwhile check before starting to disassemble parts of the transmission.
 
#19 ·
Hope this does not mess up this thread: I got my car back from my Alfa dealer yesterday, after mentioning shifting issues to them. My issue was rough shifts (felt like the plates were slipping), upon hard acceleration (in automatic mode mainly) after slowing to 5-10mph. In manual mode, I felt like I needed to force the car into 1st gear at 5mph, in order not to get the rough clutch engagement behavior. They test drove the car, agreed it felt off, and opened a ticket with Alfa technical assistance ('STAR'). STAR told them to clear the self-learn on the TCU. They did that, "performed quick clutch re-learn's" and did another road test. Problem remained unresolved. Then, per STAR, they performed a throttle body re-learn. That resolved the issue.
I drove the car home yesterday, and the performance is much better. Maybe not perfect, but the technician advised that the car will do some re-learning from my driving. We will see how it goes.
 
#20 ·
Good information.

To trigger these re-learns, they connected their system, or just disconnected the battery?

I assume the former (I think that the only transmission re-learn you can do without the diagnostic equipment is the "fine clutch adjustment", but would be happy to be corrected).
 
#23 ·
Just following up here and hopefully turning the page on this issue. I took my car up to Las Vegas to have Towbin Alfa Romeo service it, since they had recently fixed a similar problem on another forum member's car. After a lot of diagnosis (they could never reproduce the faults, go figure), we eventually decided to replace the transmission hydraulic actuator. This was based on the fault codes I had saved, the fact that replacing the actuator fixed the other car that was throwing a similar code, and also based on some back-to-back drives the dealer did with another 4C, where they noted the shift quality was worse in my car.

Happy to report that I picked the car up from the dealer and drove it back to Phoenix yesterday (~300 miles) without issue. The dealer put another ~50 miles on it to verify the repair, so I'm over 350 miles now, where previously I was seeing the fault every 5-100 miles of driving. The car also shifts MUCH better than before, with a lot less clunkiness in both manual and auto modes. I didn't realize how bad it was before, since it had been that way for the entire time I've owned it (since last Jan). So I'm very hopeful the bad actuator was the issue and I can start to enjoy this car again! I'll post back here if this same issue crops up again, but just wanted to get this info out here in case anyone else runs into a similar problem in the future.

Also, major shout out to Towbin AR, who were awesome to deal with. They had excellent communication throughout the whole process and did absolutely everything they could to diagnose the root cause before just throwing parts at the car. Their pricing was also more than fair given how many hours of diagnosis they had into it. They're by far the best AR dealer service department I've interacted with and are now pretty knowledgeable on this problem, so I would highly recommend them for anyone else on the West Coast who runs into this issue.
 
#32 ·
Great to see the fault resolved! The actuator fault is not an uncommon issue among a number of brands. Audi / VW’s have a known weakness in their hydraulic actuator assemblies within their DsG boxes. Reading the service manual functional description of the transmission gives you an appreciation for how complex these things are and how many different degraded / limp modes they can go into depending on the root cause…
 
#24 ·
Title: Transmission Issues in 2021

Hey all,

I've been experiencing transmission issues similar to those that others have had in the past, and am hoping for some help to understand how to diagnose and fix these problems. I've had the same issue three times in a month now:
  1. I drive the car for a while with no issues (the first time I had been driving the car for about 3 hours, the second time I had only driven it for about 30 minutes)
  2. Park the car and turn it off for a little bit (the first time this was only a few minutes as I filled up for gas. The second time the car was off for ~2 hours)
  3. When I go to restart the car I get the "Christmas Tree of death", reverse and manual mode are not available, and only 2nd, 4th, and 6th gears work. The first time this happened the car actually got stuck in reverse for a bit before it finally went into neutral, but then couldn't go back to reverse or into 1st/3rd/5th.
  4. No amount of key on/key off/reboots changes anything. If I pull the negative battery terminal AND let the car sit about 30 minutes, it will suddenly fire up just fine. All the warning lights go off except the CEL, all gears and modes are available, and the car shifts just fine. After driving for some amount of time, the CEL also clears itself.
  5. The third incident occurred while driving this morning. On the freeway with the cruise control engaged and car in auto mode, the transmission light briefly flashes, CEL illuminates, I get a bunch of warnings, but the car continues to shift fine in auto mode. Once I parked and turned it off, it now has all the same problems as in #3 when I try to restart it.
After the first occurrence, I took the car to the dealer and they could find nothing wrong. They double-checked the software was up-to-date (I even provided the number of the SW patch below) and confirmed there was nothing available. They then quoted me $9,000 to replace the transmission, so I took the car back and decided I would have to solve this myself.

To start, I've read all of these threads:

Transmission Failure
Transmission Failure Poll
Heads Up On a TRny Issue
Inconsistent Problems: “The Christmas Tree of Death”.

The problem is that the majority of the problems people had occurred early on, and dealers either solved the problem with a software patch which predates the build date of my car (I have a 2016) or they replaced the transmission. My car is out of warranty so a trans replacement "just in case" is not in the cards.

From what I can gather, these are the possible sources of the problem. Is this list complete and in which order should I troubleshoot this?
  • Clean/brush battery terminals and add dielectric grease - already tried this after the first incident, didn't solve the problem
  • New battery - I tested the battery at Autozone, they claim that it's totally fine, not even marginal on startup
  • Get the software patch that worked for others (CFC8TDW.01-00-UF14M080) - I gave this number to the dealer and they claimed everything is up to date
  • Check/refill "Robot mechanism" (shift actuator?) fluid level
  • Replace shift actuator pressure sensors with this part: Pressure sensor - Alfa Romeo TCT - SequParts
  • Replace voltage regulator for shift actuator
  • Replace hydraulic actuator p/n #68303710AA
  • Replace transmission
Also, is anyone aware of an Alfa tech or indie shop somewhere in the US who actually has experience troubleshooting and solving these issues? The tech at the local dealer had seen this problem many times on Fiat 500Ls, but said that they just R&R the transmission every time, so he didn't have any idea how to diagnose the root cause.

Any help would be appreciated, I don't feel like I can trust my new car enough to drive it anywhere until this gets sorted out.
Hi, My 4C has 70.000 Km and I experience the same problems now. I am using the Multiscan 4.7R3 tool and did all Adjustements. In the Production/Service final calibration procedure, all elektrovalves, potentiometers and mechanical components of the whole actuation unit, are tested. So, in your case, it would also test the integrated sensor module. So my suggestion is to run this test and than do the clutch self-calibration enable. In my case I first got the error code related to the electropump of the power unit. I changed the electropump,the accumulator and the elektronic control unit of the elektropump, but without any succes. During a trip in the Italian mountains, I got the same problem. Now I am going to replace the clutch, because with 70K and at least 50% driving in the mountains, I think the best is gon and the clutch is worn.
 
#25 ·
Sorry to hear you're having the same issues. I suspect we will see more cars have this problem as time goes on. Good idea on the testing - hopefully that helps someone in the future.

In my case, the electropump was fine. The hydraulic actuator was the issue. With a new actuator, the car shifted much more smoothly and no more errors. I have about 2,000 mi (~3200 km) on the new actuator and have had zero problems. Did you get the same trouble codes as I originally got (P1C9900)?

I would suggest looking into the actuator before clutch replacement. Or, at the very least, inspect the clutch and if it's not worn, I would look hard at the actuator. In my case, the dealership was able to pinpoint the problem by driving my car back-to-back with another 4C and the difference in shift quality was immediately noticeable. That plus their previous experience replacing the actuator to resolve the same codes, led them to replace the actuator on mine. I know back-to-back test drives is not always doable, but they got a little lucky.
 
#31 ·
Yes, I should add the TCM as a potential culprit. I will definitely pull off the shield and connectors and inspect the connections for water intrusion, but I'm guessing it's not the issue here (see below).



I put the car on a Battery Tender after the first occurrence just in case, but it didn't prevent the last two happenings. I'm still keeping the battery on the list of problem areas though. The AZ heat is known to kill batteries and if this is the factory battery, it's end-of-life anyway.



I could definitely see this being an issue, as I actually lived through this problem (water intrusion via wire harnesses) with an automotive component I designed at my job several years ago. However, I would be surprised if it's the problem here - I live in AZ where it's very dry all the time, and when I wash the car I use Optimum No-Rinse, which means that I don't even hose the car down. So if any water is getting in the engine bay, it's a few drops at best. The car did come from Florida and Virginia though, so it's not impossible there was existing corrosion before I bought it.
Nate - There are some clues in what you describe that lead me to believe it is more voltage / input error related than mechanical. The clutches for even and odd gears are controlled separately with the odd via a distance sensor and the even via a pressure sensor any fault with these would show up as an even or odd gear unavailable and no manual shift.
If the actuator fluid level is ok then I wouldn’t touch this other than a minor top up - it could add another set of variables to your problems..

The fact yours come up with Christmas tree errors on start up suggests voltage or earthing issues or a TCU problem. Early models did not have a rain shield fitted over the TCU which sits directly under and gap in the panels and drip line. Water ingress to the top of the TCU plugs could definitely cause a short - have a look for signs of water ingress and pull the plugs out and inspect they are dry and not corroded. Install a make shift rain shield over the TCU. If the battery is more than 3-4 years old I’d get a replacement anyway just to rule it out and I’d go and inspect all the earthing point and make sure the terminal posts / fasteners are tight and corrosion free.

The next thing to do would be aTCU swap and if there is still problems then it’s time to start looking at the transmission itself…
 
#33 ·
Hello, My name is George from Greece and I own a 2015 4C. I have the same promlem with transmision. I already 35.000km. After driving 45km the gear box goes to safe mode and I can the car goes to auto and use only the 2nd 4th and 6th gear. when I go back home and leave it all night, the next day its everything fine! I drive about 50km and the issue appeared again! do I have to change all the transmision? The failure coed is P0914 any ideas
 
#40 ·
The position sensors are together in a module that is part of the robot. This module is not available separately. The chance of these breaking is also very small, but it may be that they are soiled with small metal particles that come out of the gearbox. The robot is fairly easy to disassemble.
The sensors themselves can be tested, with the Multiecuscan it is possible to operate the robot and test all gears without the motor running. The position sensor of the clutch or the position sensor of the shifter can also be a cause here.
The entire system is also tested during a recalibration of the robot / gearbox. So I would do these tests first.
I would certainly change the oil of the gearbox and definitely the oil and filter of the robot (after cleaning the sensors)
The pictures show you the sensor module disassembled and the robot with the module mounted.
What you should also do is check the electrical wiring and treat the connectors on the robot and the TCU with a good contact spray.



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#43 ·
SW version: you can check this with the Multiecuscan, or with the factory tool from your dealer.
Fact that the car is ok for 45 Km is proof that nothing is wrong with the gearbox.
Problem is with the robot and your dealer will propose to change the complete robot because this is recomended by the factory.
To check:
SW update for TCU
Actuator test for all gears
Check hydraulic pressure during these tests. It should not drop under 42 bar. Hydraulic pump should run when opening door, pressure should go up to 52 bar. With engine off, contact on en brake pedal on, switch gears from N to 1 to R and back to N. Monitor hydraulic pressure. When prussure is under 42 bar, the pump should run again. If not, problem with hydraulic elektric motor, pressure sensor or accumulator. (hydraulic power unit)
If all this is OK, run the complete calibration procedure but I would suggest to change the oil and filter of the hydraulic system befor doing that.
Al these tests can be done only with OBD tool, e.g. Multiecuscan.
 
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