508 RXH Hybrid4 won't start- U12C6

[vic678]

Hello and nice to meet you guys. Guess i'll have to introduce myself first. I'm on my first french car. 2011 508 RXH. Till now i was mostly on german, korean or japanese but mostly german. Now my other car is also german, a VW.

I bought the RXH as i liked the looks and feels inside the car. It was basically am impulse buy, did not research much. I just knew that french diesel engines are tough as nails so i though wow cool, diesel hybrid, sounds really interesting.

First couple of months was pretty troublesome. As i used it mostly for short trips 3-4kms at once, basically to take kids to school.

Now first major issue occured about a year ago. I was driving out of a residential area and once i hit the road i have accelerated from 10-15 to 45-50kmh to get ahead of the other cars. At that point the red ENGINE FAULT message popped on the dash and the steering got stiff. I have barely managed to get it to the rightmost of the road, it let me drive about 50-70 meters till it stopped completely. As it happend for the first time (spoiler it happend in several months again after that) i thought i will just "restart" he battery for some 30 seconds, the error will clear and i will try to start it. It did not work of course so i have called for the tow and got it to my regular service mechanic guys that i used to service my other cars before.

The read the errors with Autel, there were at least a dozen but they told me the problem is with BSI, they opened it and it looked like it burnt. So they told me i needed to find another BSI and bring it to them for replacement. I did find one from another donor rxh. They swapped it in and miracle have happened. The car would start and run. Yes there were still some errors left but i did not care at the time as i was thinking to take care of them a little later.

Fast forward 3 months and about a 1000 km same situation happens. I have accelerated from 10-15 to 50 kmh and the car shuts down. Exactly same situation. I'm towing the car to the same guys. After a couple days they tell me it's highly likely the tration battery is dead. And they can't go past it with their diagnistics. I have taken the battery to other guys who have tested each cell and overall the battery was at 55 percent. I know it's not a good sign but i thought that it's strange that the car won't start at all so i decided to tow the car to Peugeot's official dealer. They tried their magic to make it start but it did not work out. Next day they called me telling that the traction battery is too weak and i should buy a new one or bring them a healthier one. I took the battery to another shop that did some magic and got it up to 80% capacity. So i brought the battery back to the dealer and now miraculously they were able to go past the battery in their diagnostics investigation and now they tell me the problem is highly likely with the alternator and that i gotts bring them a new one so they could try it and see if it's really the case. Since it's an old model they don't have those alternators in stock.

I thought it's not a cheap gamble to take on. Based on the previous example with the battery that eventually was not the cause of the problem as it appeared, i was not sure i want to spend some Eur2000 just to cut away a possibility.

They also told me that if it's not the alternator then maybe it's the invertor or the wiring in between.

At that point they told me that they cannot help me with anything unless i bring them a 100% confirmed functional alternator to move forward. So i had to find someone else willing to jump on the task.

So final chapter, i know it's already a novel but stay with me for final couple phrases. The guy that the car is with now, for last 2-3 months already, has managed to start it but it runs 1-2 seconds and stops. He told me that he did not believe that BSI was burnt the first time. He checked it and saw no damage except from the opening on the plastic cover by the guys at the first shop. He cleaned everything and swapped it back in. Now interesting thing is that more than half of erros have gone. The car sees the old BSI and it's fine.

Now question is (before we move on to the error codes) what do you guys think could cause the car to behave like that. To shut the engine after an acceleration. I had 2 instances in same conditions, but after the first one the car was made to start again and drive ok-ish (although not for too long)
Could it really be because of the alternator ? Shall i look for a donor one to try to eliminate this possibility (or maybe it is the cause and the car would start and run) Or it doesn't sound like a alternator could be "disturbed" by a sudden acceleration and get the car into shutdown.

Now as far as i know the main errors are U12C6 and P0949 (both errors were present after the first shutdown instance and after the second one too) I know that P0949 refers to the gearbox but could it impact the non start behaviour ?

Not much hope, but any idea, advice would be helpful, so that at least i know what could we try next to make it run again.

Here's the vin VF3**************[VIN obfuscated, can be read by forum staff]

Thanks

[vic678]

Status update. Nothing yet.

Car not starting. Errors :

U12C6
U0167
P1ABF
P1AC4
P0215
P0949

[GiveMeABreak]

Piloted gearbox issue aside, all these seem to point to the Hybrid ECU.....

Fault Code:	P0949
Description of Fault:	Clutch programming incomplete or not carried out fault: Not characterised. Description of the diagnostics: Detection that the bite point has not been programmed The time of appearance of the fault code is 1s Context of appearance of the fault code: The following conditions have to be met: - ECU woken up -Ignition on for at least 5 secs
Conditions for Fault to clear:	-
Downgrade Modes whilst Fault is active:	Controlled manual gearbox ECU re-initialises the bite point
Symptoms:	Lack of power
Suspect Areas:	Controlled manual gearbox ECU

Fault Code:	P0215
Description of Fault:	Main relay: Poor operation of the relay, the ECU is not being supplied as it should be. Description of the diagnostics: Possibility 1 Engine ECU still supplied for 2 s despite a request for cutting of its supply Possibility 2 Loss of supply of the engine ECU for 2 s without a prior request being detected, due to an incorrect value memorised at the following wake-up Conditions of activation of the diagnostics: The following conditions have to be met: - Ignition on - Indicator lamp READY lit
Conditions for Fault to clear:	Driving for 5 minutes
Downgrade Modes whilst Fault is active:	Problem activating the power unit
Symptoms:
Suspect Areas:	Service battery Hybrid control ECU Battery terminals Electrical harnesses Connectors

Fault Code:	P1AC4
Description of Fault:	Drive train: Failure of the activation of the electromotor sub-assembly. Description of the diagnostics: The electromotor sub-assembly is not activated after 2 s for a partial activation request or 3 s for a total activation request. Conditions of activation of the diagnostics: The following conditions have to be met: - Ignition on - Indicator lamp READY lit
Conditions for Fault to clear:	3 activations/deactivations of the electromotor sub-assembly
Downgrade Modes whilst Fault is active:	Deactivation of the "Stop and Start" function
Symptoms:	Problem activating the power unit Absence of automatic stopping of the internal combustion engine
Suspect Areas:	Hybrid control ECU

Fault Code:	P1ABF
Description of Fault:	Motor: Absence of coupling. Description of the diagnostics: Failure to couple the reduction gear after 3 attempts Conditions of activation of the diagnostics: The following conditions have to be met - Ignition on - Indicator lamp READY lit
Conditions for Fault to clear:	Issue 3 coupling requests (shifting gears) after repair
Downgrade Modes whilst Fault is active:	Driving possible only in combustion mode Switching on of the warning lamp and/or warning message: "SERVICE" warning lamp.
Symptoms:	Lack of power Absence of the electric mode Absence of automatic stopping of the internal combustion engine Banging/knocking/creaking
Suspect Areas:	Motor Electric traction machine

Fault Code:	U0167
Description of Fault:	Intersystems CAN: Absence of response to the unlocking request. No response from the built-in systems interface following an unlocking request from the hybrid control ECU 1. Conditions of activation of the diagnostics: The following conditions have to be met: - Ignition on - Indicator lamp READY lit
Conditions for Fault to clear:	Driving for 5 minutes
Downgrade Modes whilst Fault is active:	Deactivation of the "Stop and Start" function
Symptoms:	Absence of automatic stopping of the internal combustion engine Problem activating the power unit Jerking/stalling (Stopping the vehicle)
Suspect Areas:	Hybrid control ECU Built-in systems interface Intersystems CAN

Fault Code:	U12C6
Description of Fault:	Hybrid CAN Control network: Length error or prohibited value of the frame from the hybrid management ECU 2. Communication fault between ECUs detected for 0,5 secs. Conditions of activation of the diagnostics: The following conditions have to be met: - Ignition on - Indicator lamp READY lit
Conditions for Fault to clear:	Ignition on
Downgrade Modes whilst Fault is active:	Irreversible deactivation of the vehicle cruise control (Need to switch the ignition off and then on, in order to make the function available again). Irreversible deactivation of the vehicle speed limiter (Need to switch the ignition off and then on, in order to make the function available again) Driving possible only in combustion mode Loss of the ZEV (Zero Emission Vehicle) electric mode Loss of the 4x4 function Loss of Sport mode Deactivation of the "Stop and Start" function Switching on of the warning lamp and/or warning message: "SERVICE" warning lamp
Symptoms:	Absence of the electric mode Lack of power Absence of automatic stopping of the internal combustion engine Cutting of the vehicle speed limiter Cutting of cruise control
Suspect Areas:	Hybrid control ECU

[vic678]

Thanks Marc, i have read many other threads with guys with similar symptoms and similar errors and 80% of the cases it was because of the alternator belt. In my case though the belt still looks fresh, with all the inscriptions on. Is there a way to test the belt without having to tow the car to Peugeot dealership again. At the dealership they would have probably noticed the previous time, for 3 months that car stayed with them if the belt was the problem, right ?

[GiveMeABreak]

It's hard to say as I don't know the circumstances, but all I can suggest is that they will diagnose it and follow the guidance. Unless there's a known reason to test other components not explicitly referred to in any diagnostic, they may not touch the alternator, so impossible for me to say - and I guess it would be down to the real world experience of each technician as to whether they know historically of other issues. But the dealers do have access to the technical documents and a hotline to France for support if they require it.

[vic678]

Let's keep the error codes aside and just analyze both situations that have cause the car to "shut" and throw the engine fault messages.

In both instances i have tried to speed up, from 10-15kmh to like 50, aggresively. What would have come under stress and potentially fail (maybe there is a bottleneck that under normal lean acceleration and driving resists yet when it's stressed it fails) ?

So my question is what happens in the care when i press that acceleration pedal ? My understanding is car "needs" more traction/momentum and so it triggers the rear wheels, also the alternator works as an electric engine providing additional power, also the rear electric motor gets under stress.

[vic678]

It's hard to say as I don't know the circumstances, but all I can suggest is that they will diagnose it and follow the guidance. Unless there's a known reason to test other components not explicitly referred to in any diagnostic, they may not touch the alternator, so impossible for me to say - and I guess it would be down to the real world experience of each technician as to whether they know historically of other issues. But the dealers do have access to the technical documents and a hotline to France for support if they require it.

I have stumbled upon a thread on a french forum where people mainly complained about how it is such a pain to diagnose these cars until the last post by a guy who explained that once the 12V battery voltage drops below a certain level, the Hybrid battery gets too much damage and in some cases it leads to some sort of fatal error that gets stored in BMS (battery management system). That throws all those nasty messages on the dashbord and shuts down the car. So to start the car he suggested you need to press the ECO mode off, on that drop down panel below the steering wheel and after that the diesel engine should start. Now do you guys know if that BMS is possible to access through diagbox and erase the error ? Is it a separate thingy or it is incorporated into some ECU ? HCU, or maybe battery itself.

[vic678]

So upon further research the aferementioned BMS is TBMU - traction battery monitoring unit. It's somewhere within the battery case.

Digging deeper...

[Serik]

Hello everyone! I have the same errors. How did it all end for you, did you solve the problem?

[Doom]

Hi Serik,

A few weeks ago I bought a 2nd 508 Hybrid4 car. I already have one. New one have tones of errors and it was cheap because didn't start. Most important for cars is to have a good 12V battery. First what you should do is to check if your is good. At least charge it fully. Gearbox errors are usually caused by bad 12V battery. In my case, charging allow me to erase most of the errors and reinitialize gesrbox. All errors related to gearbox was caused by drained 12V battery. If control units don't have proper power they are generating many random errors. After charging 12V battery I was able to start car ( after erasing all errors using Diagbox - clone is not very expensive). It's not end of the problems in my case as rear differential bearing broke - Peugeot don't recommend oil change ( after 400k km bearing in very old oil decided to retire )

Second common issue is accessory belt. It's important to use OE parts (original PSA parts). If it's loose it will generate errors - ECU sees when engine speed is higher than alternator and popups error. Common problem is belt tightening (if it's new) or alternator bearings ( they can cause issues every 100-150k km). If car runs for longer time before issue, check belt, if it's loose (it should be very tight because it's working in 2 ways, it needs to start the engine and charge traction battery). If you remove belt to replace it, check alternator bearings, spin it and it should rotate freely and should be quiet. It's possible to replace bearings - they are not so expensive.

To summarise, charge your 12V battery - erase all errors using Diagbox, check what errors stay. If engine still not starting (start car with eco mode off) check errors again. They can be related to accessory belt. In my case even if rear electric engine was damaged, combustion engine started and running good. For gearbox error probably you need to reinitialize it - it's easy if you have Diagbox.

[vic678]

Fresh update.

The alternator was blown. I can post pictures of what was inside after we've opened it. I suspect a botched bearings replacement by the previous owner that set up some sort of wreckage inside after some (not that long) time. As i have managed to put in no more than 2000kms after i bought it before it died in the middle of the road after i have revved the engine.

So now the car starts and drives but only in 4*4 mode. First day after more than a year, so i'm taking it slowly. Filled up the tank to dillute the remaining 10-12 ltrs of old diesel.

I have 2 errors in HCU1 now P1AD8 and U0167 (this was was before too, so i'm hoping it clears after i drive for a couple tens of kms)

There are some BSI related errors , door handles etc. 1 error in engine ECU, specifically P12A5 - low compression in 2nd cylinder (hopefully goes away after some driving)

So now i wonder if there is something i should try to get the car getting to Auto mode.

Cheers