MOT Failure Peugeot 508 P1A9C Energy Accumulator fault after flat battery

[ben341]

Hi all,

I have 2012 Peugeot 508 1.6 e-hdi with 60k miles on it.

In December 2022 I attempted to start the car and it wouldn't fire up, it would crank but battery was obviously low. I called RAC to rectify, they installed battery described on their invoice as 444RAC011, 096 AGM Battery, I noticed the brand is Varta.

The RAC person then read the following codes which had appeared:

DTC: P1A9C,Energy accumulator. State of health fault
DTC: P0500,Speed information faulty
DTC: P0685,Power relay

All of this appears with the "Engine Fault, Repair Needed" fault but with no permanent MIL lamp on.

A few days later I took it to a Peugeot specialist to check it over and have new fuel filter installed as it was due. The codes other than P1A9C had already cleared but he couldn't clear this one. He advised me it would likely cost £1000 to fix and its just the stop/start system and won't be an MOT failure.

I took it for its MOT a couple of weeks after that in Jan 23 to a local Halfords, and they didn't fail it. They placed an advisory something like "Engine reporting fault, not MIL"

I have driven it around 4k miles since then, had cambelt done, service etc, not had any problems at all with the car, quite happy that I now didn't have to manually turn off stop/start every time I started the car.

I've taken its 2024 MOT today and they have failed, saying MIL is on. I asked them to check whether this is really the case, pointing out that in 23 it passed and the code confirms it isn't a fault with the engine itself. He called the DVSA and they told him to definitely fail it.

I'm really not sure what to do. I don't want to sink £1000 into it only to find issue remains. There is really nothing other wrong with the car, never missed a beat, has good service history, low usage etc. I also don't want to get rid of it.

After RAC came I wondered if new battery had a missing connector that he didn't connect or something similar. I believe the battery is of the correct type. I took the cover off back then and couldn't see anything disconnected.

Is it possible that the attempt to start the engine with it unable to crank enough caused damage to the accumulator and therefore replacing it a wise choose? I've done a lot of reading on here since then and people are having that either resolve the problem or not make any difference. I guess I'm wondering where to look first, and whether it is more likely to be damage caused by the failed start-up attempts or something not done correctly during the battery swap procedure. I don't think my alternator has a problem, original battery was overdue for replacement and had failed during sub zero temperatures. I usually drive just 25 miles a week often not touching it for a week at a time and it will fire up perfectly after sitting there, and then some weeks I'll do a few 120-250 mile journeys which is where it gets its mileage from, so its getting an ok mix of driving types.

Any feedback appreciated please.
Thanks very much.

[GiveMeABreak]

This has nothing to do with the car battery, it's to do with the energy accumulator in the vehicle. Basically it has a capacity-type device that stores energy up and uses this to start the vehicle in some Stop & Start vehicles. It's hidden way under the wing and this fault code is likely to do with this accumulator and not the battery.

Fault Code:	P1A9C
Description of Fault:	Energy accumulator: Energy accumulator state of health fault. The state of health of the energy accumulator is detected at the low limit for 0,48 s.
Conditions for Fault to clear:	Ignition on
Downgrade Modes whilst Fault is active:	-
Symptoms:	"SERVICE" warning lamp Absence of automatic stopping of the internal combustion engine Malfunction of the Stop and Start switch or its LED
Suspect Areas:	Terminals of energy accumulator and voltage retaining device Energy accumulator

[ben341]

Thanks. Do you have any idea whether it would be normal for an MOT to fail due to this? I understand stop/start in these cars is part of the official emissions level and wonder if that is the justification.

It occurred to me when you said this is in the passenger side wing, I cracked a spring and mcpherson strut mounting in December 2019 on a large speed bump on that wheel and needed them replacing. Is it possible the mechanics that did that had to work around the accumulator system and may possibly have not fastened it together tightly enough? A lot of threads regarding this accumulator seem to suggest the issue is more frequently to do with the wiring of it rather than a failed capacitor directly.

Thanks for response.

[GiveMeABreak]

No, it's not the actual Stop / Start system that they can fail you on, as you are legitimately allowed to turn that off before each journey if desired. It's to do with the Malfunction Indicator Light (MIL) or Engine Malfunction Light (EML) that they are picking you up on.

Section 8 of the MOT under 'Nuisance' shows this under 'h':

(h) Engine MIL inoperative or indicating a malfunction - Major

So you likely got away with it on the first MOT.

So even though this may not have anything to do with emissions or 'nuisance' of exhaust, the fact that the light is on is a failure.

Here are those other fault codes that may be of some use:

Fault Code:	P0500
Description of Fault:	Intersystems CAN: Speed information incorrect or absent. Information not received or received invalid by the engine management ECU on the CAN. Conditions of activation of the diagnostics: Ignition switched on.
Conditions for Fault to clear:	Driving for 5 minutes
Downgrade Modes whilst Fault is active:	Irreversible deactivation of the vehicle speed curbing function Irreversible deactivation of the vehicle speed limiter Irreversible deactivation of the vehicle cruise control Sending of the information "torque uncertain" on the CAN network Switching on of the warning lamp and/or warning message: Warning lamp MIL
Symptoms:	Jerking/stalling Lack of power
Suspect Areas:	Engine ECU Intersystem CAN network

Fault Code:	P0685
Description of Fault:	Power relay control: Open circuit. Electrical fault detected for 5s. Conditions of activation of the diagnostics: At least one of the following conditions must be fulfilled: - Ignition on - engine running
Conditions for Fault to clear:	Driving for 5 minutes
Downgrade Modes whilst Fault is active:	-
Symptoms:	Jerking/stalling Lack of power Starting problem
Suspect Areas:	Power relay Electrical harnesses Connectors

As for the knock you had under that side when the spring went, it also possible it has damaged something else. I would certainly start by checking all the connectors at the engine ECU and making sure these are not loose or anything in that area that could of been damaged by the vibration / shock.

[ben341]

Thanks. The panel MIL lamp doesn't stay on however, which is why I was confused.

I have just called the garage it and doesn't sound like good news, he listed off around 8 different codes now, relating from speed, steering, aircon, open relays etc, sounds knackered. I will list them here when I get the car back with the report but I don't know if its going to be worthwhile to fix, I can't seem to find a local auto electrician that has decent reviews and can't really afford to sink hundreds into potentially incorrect diagnosis and still not have a working car. I've got to be honest and say I've noticed any faults at all. Maybe I will be lucky and the wide ranging faults are actually related somehow.

[GiveMeABreak]

Yes, be aware that if there is a CAN fault, this can easily have a knock-on effect on other systems as the CAN carries data to various ECUs along the way, so if any of those are getting faulty data, it will trigger a fault on those systems too.

The MOT checker can't fail you on a MIL that turns on then off, as this is what they are supposed to do. So if the ignition is turned on, it is supposed to light up and then go out. That is normal. When you do get the codes back, post them up along with your VIN so I can ensure the codes are specifically associated to your vehicle.

[ben341]

Thanks I just got car and report back:

Couple below seem to relate to No1 injector, possibly something going on there but am not noticing any roughness or loss of power that would normally be associated with a bad injector/cylinder.

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

All the codes are:

P0685 Power Relay Control: Open Circuit
P0263 No. 1 Cylinder: Injector Resetting Outside Tolerance
P1A9C Energy Accumulator: Energy Accumulator State Of Health Fault

Transmission
P1750 Steering Wheel Gear Control Signal Short Circuit To + Or Open Circuit

Battery Charge Status Unit (If Fitted)
B162C Fault: Accessories Positive Relay Control And Status Not Coherent : Relay
Commanded But Inactive
B1805 Starter Fault

BSI
B162C Fault: Accessories Positive Relay Control And Status Not Coherent : Relay
Commanded But Inactive
B1805 Starter Fault

COMM Switch
B1181 Lighting And Signaling Control Fault
Page: 1 2012 Peugeot 508 1.6L T­Diesel (9HR) Date: 09/01/2024 5:44 PM

Engine Relay Unit (If Fitted)
B1300 Aircon Compressor Clutch Control Fault
B1301 Control Fault Of The Variable Swept Volume For A Displacement Air
Conditioning Compressor

Radio
B1502 Fault On The Right Hand Front Audio Output : Open Circuit

Right Hand Windscreen Wiper Motor
B11B1 Fault In The Wiping Reference Value From The Built ­ in Systems Interface

Supply Protection And Management Unit (If Fitted)
B162C Fault: Accessories Positive Relay Control And Status Not Coherent : Relay
Commanded But Inactive
B1805 Starter Fault

Telematic
B162C Fault: Accessories Positive Relay Control And Status Not Coherent : Relay
Commanded But Inactive
B1805 Starter Fault

OBDII Codes ($03)
P0263 Cylinder 1 Contribution/Balance

[ben341]

I've checked the connections around the ECU to make sure they were seated correctly and there was no give in them at all. (this area https://pmmonline.co.uk/wp-content/uplo ... -fig-2.jpg )

It doesn't appear if any of those fuses are blown. There are connections entering that fuse box from below as far as I can tell but that is obviously out of reach. Bump related damage is a good call but the repair took place exactly 2 years before this problem appeared, was thinking something gradually worked loose. With that time difference however, and the fact this started immediately after I had attempted to start the car with a flat battery, and code/problem appearing as soon as car was powered on with new battery, leaves me thinking some electrical damage may have taken place during the failed start attempts.

[ben341]

Just to add more detail to the scenario when problem appeared. It was early Dec 22 and we'd had a -10 cold snap or something. I had to drive to Leeds next morning so decided the evening before to check car was OK as I hadn't used it in a few days. Starting with the key it would crank 5 or 6 times, obviously slowly but not slow enough for me to think it was impossible to start. I repeated the process, this time waiting for the glow plug light to go off first, which isn't something I'd normally have to do. The glow plug lamp took quite a few seconds but did go off and i tried again. Repeated about 4 times hoping to at least get it somewhere I could get a battery. I gave up. During my attempts, the dashboard was going haywire, which I've found isn't too unusual when the car is flat. I'm wondering if this has damaged something.

I did consider walking to halfords which is 5 min away but their website put me off buying a battery myself saying that some cars need them coding, so decided to call RAC. They started it with a jump pack then did the sales speech about how I needed a new battery, which was £80 more than equivalent at Halfords I was going to buy. He said it didn't need coding.

New battery in, car fired up fine, he put diagnostics on it and got those first 3 codes which I coped from the RAC report they emailed me. I took car for around a 20 mile round trip to make sure everything was fine, it seemed to be. Next time I turned car on it gave the engine fault, repair needed warning, S&S wouldn't function and it has been the same since.

I took it to a Peugeot specialist a few days later to get him to look and to change fuel filter. He said something strange about the starter, that it has to kick backwards for the S&S to work and maybe it isn't doing that? This isn't something I know about, but obviously there are a couple of starter fault codes in there. Would be happy to have that changed if I could be sure it was the problem. As I've said all along though, no reliability issues, no hint of weak starter, fired up immediately that snowing sunday in Dec we had after not being used a few days. Just baffled. I'm not trying to get out of doing essential work, its just the worry of spending hundreds and still having it not fixed...

Anyway I called my local Halfords garage that passed it with an advisory in 2023 yesterday and he told me to let them look at it today. I took it at lunchtime. One of the MOT testers took a good look at the legislation, looked at the car, the fact the MIL light goes off (actually took 4 start attempts to even get it to show engine fault on the screen) and he said he would have given an advisory. He checked with his VOSA contact who said the same thing, so they've agreed to squeeze it in for a test with them on Sunday. Overall though, there's obviously something going on, I'd like to try and get it resolved as I am hoping to keep the car for years more, its been a great, comfortable car except for this annoying issue.

[GiveMeABreak]

Fault Code:	P1750
Description of Fault:	Gear controls at the steering wheel signal fault (Gear shift paddles): Open circuit or short circuit to the plus. Gear shift paddle signal greater than the maximum threshold of 4,5 V. The time of appearance of the fault code is 2s. Context of appearance of the fault code The following conditions have to be met: - Ignition on - The starter motor is not operating Technical precision on the context of appearance of the fault code: Supply voltage correct
Conditions for Fault to clear:	No faults for 2 seconds
Downgrade Modes whilst Fault is active:	Gear shift controls at the steering wheel not operational
Symptoms:	Difficult/impossible to change a gear
Suspect Areas:	28-way connector of the piloted manual gearbox ECU 28-way harness of the piloted manual gearbox ECU Gear shift paddles Supply of piloted manual gearbox Gearbox ECU

Fault Code:	B1805 62
Description of Fault:	Coherence fault: starting request with no drop in voltage: Not characterised. Description of the diagnostics: The drop in voltage linked to the activation of the starter motor does not occur (Drop in voltage greater than 1,5 V). Conditions of activation of the diagnostics: The following conditions have to be met: - Ignition key in starter position (Seen by the BSI and for a set duration) - Automatic gearbox in park or neutral position - Foot on the brake pedal and gear lever on Neutral (For vehicles with piloted manual gearbox (BVMP))
Conditions for Fault to clear:	At least one of the following conditions must be fulfilled: - The drop in voltage linked to activation of the starter motor occurs correctly - The key is in a position other than starter+ (+DEM)
Downgrade Modes whilst Fault is active:	-
Symptoms:	Starting problem
Suspect Areas:	Configuration of the engine management ECU Starter Ignition switch Electrical harnesses Engine ECU Gearbox ECU Stoplamp switch Gear lever Engine fusebox Built-in systems interface Configuration of the engine relay unit Authorization information to start Fuse protecting the starter motor control Fuse protecting the ignition switch

Fault Code:	B11B1 81
Description of Fault:	Fault in the wiping reference value from the built-in systems interface: Reference value absent or not valid. Absence of wiping reference value or wiping reference value not valid for more than one second. Conditions of activation of the diagnostics: The following conditions have to be met: - Ignition on - Apart from in economy mode
Conditions for Fault to clear:	Transition to valid customer reference value received
Downgrade Modes whilst Fault is active:	Maintaining of the last valid reference value received, at least intermittent wiping at 4,5 s
Symptoms:	Reduction of the wiping angle Random wipe in slow speed (With no command)
Suspect Areas:	Master wiper motor (On the driver’s side) Built-in systems interface LIN network

Fault Code:	B162C 11
Description of Fault:	Fault: accessories positive relay control and status not coherent: Relay commanded but inactive. Description of the diagnostics The control of the accessory positive relay is active even though the output of the accessory positive relay is inactive. Relay commanded, accessory positive supply inactive (Voltage less than 5,6 V). Fault confirmation time: 1s Conditions of activation of the diagnostics: BSI triggered
Conditions for Fault to clear:	The following conditions have to be met: - Control and output of the accessory positive supply relay active - Relay commanded, the accessory positive supply is considered active when its voltage is higher than 5,6 V Time of disappearance of the fault: 1 s
Downgrade Modes whilst Fault is active:
Symptoms: No supply of electrical components
Suspect Areas:	Fuses Connectors Built-in systems interface Supplies protection and management unit

[xantia_v6]

I have the impression that some of those codes were triggered by attempting to start the car with a flat battery.
Were the codes cleared? If so which ones returned?

[ben341]

Thanks Xantia. Not all those codes were visible immediately after the battery was changed, only 3. I didn't check codes until the garage did them yesterday, some of them are new. I don't know if he cleared them and if they returned. I've bought a basic obd2 scanner to try and read them again and then I'll clear and see which ones return.

My feeling is there is likely some component that needs replacing, maybe dodgy relay or PCM that is linking them all together. The codes read the other day will have developed some time in the 12 months since the battery was changed. What is odd, with the large number of codes, and the seriousness of some of the symptoms, I'd expect to be noticing something, but I have 0 of the symptoms except stop start not working.