Peugeot 508 Hybrid4 RXH 2012 hybrid train fault. U0167 + P1A79

[impaelas]

Hi all,

VIN: VF3**************[VIN obfuscated, can be read by forum staff]

New guy here desperately looking for a solution to a repeating issue.

Car got into a limp mode. When checking codes via Diagbox noticed two errors in the Hybrid control ECU 1 occurring simultaneously. I've noticed that the ancillary belt tensioner was very wobbly so it got changed together with the belt. Hope was that the alternator had slipped thus causing the error with the hybrid train. It didn't. Today limp mode again with these two errors (listed below) popping up with same mileage.

If it helps, I often get electric mode unavailable when driving and it seems to be occurring with no noticeable pattern.

P1A79 Drive Train
Cause Local
Status Permanent fault
Vehicle mileage190480Km
Traction battery voltage218.5V
Current of the traction battery9.7A
Electromotor sub-assembly started
Characterisation of the fault Starting does not conform

+

U0167 Intersystems CAN
CauseDistant
StatusPermanent fault
Characterisation of the fault Absence of response to the unlocking request
Status of the ECU Unlocked

Thank you all.

[impaelas]

Bumping this up just in case someone can help. Still having issues.

[GiveMeABreak]

Here's some further info on those fault codes. As you can see the reversible alternator and starter play a significant part for the first fault. However the Hybrid ECU is common to both faults, and if it id determined that this is the fault, it means a complete traction battery as the ECU is integrated and not available separately, so focus on the other suspects first in your troubleshooting.

Fault Code:	P1A79
Description of Fault:	Drive train: Starting does not conform. When there is a start up request, the reversible alternator and the starter are not operational. The following conditions have to be met: - Ignition on - Indicator lamp READY lit
Conditions for Fault to clear:	-
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). Switching on of the warning lamp and/or warning message: Warning lamp STOP & "SERVICE" warning lamp
Symptoms:	Problem activating the power unit Cutting of the vehicle speed limiter Cutting of cruise control Lack of power Absence of the electric mode Absence of automatic stopping of the internal combustion engine
Suspect Areas:	Starter Reversible alternator Hybrid control ECU

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

[impaelas]

Thank you mate. I was trying to find tests in Diagbox that would help me narrow it down. Finding shops that are willing to troubleshoot this is impossible around here and Peugeot will simply want to replace everything and I only have two kidneys which I am very fond of.

I think my best bet at this point is checking the status of battery cells. They haven't been touched in 11 years and from what I am seing on later models P1A79 was resolved with replacing cooked cells. Will update when I find something. If anyone has other useful input thanks in advance.

[GiveMeABreak]

You're at about the life span of the batteries IIRC, but hopefully the starter, alternator will give you some more options to check, but understandably, special training is needed when handling traction batteries, so many places currently will not be equipped or trained to deal with the risks associated with these, yet alone do any work on them...

[impaelas]

Update. I did some tests time permitting and my conclusion is that while ECO drive is disabled (basically diesel engine is not switched off while electric drive is used) the error doesn't show. While city-driving with many start/stop activations eventually the error will pop up.
Am I wrong to assume starter is a likely culprit? I have ruled out alternator on account of it having to be 100% operational in either scenarios.

Thanks guys, you are a lot of help.