2015 C4 Picasso - Battery Change Error (BSI Reset Fail)

[kenykl]

Hi all,

I have changed my flat 12v battery with a Bosch S5A08 battery for my 2015 mk2 c4 Picasso. Seems that I haven’t gone through the procedure correctly, it prompted up “engine fault” with “emission fault”, with the OBD reader, it says P20E8. I learnt from another FB user with the same car model and changed with the same battery also have the same error code, seems to be a random code for this battery. I tried to reset the BSI following the procedure, it seems does not work. Noted that we need to turn off everything in the car first, wonder how to turn off the radio as if we press the power button on the dashboard, it seems only mute the radio, will it be okay for BSI reset? Another question is whether I can unplug the positive terminal rather than the negative terminal for the BSI reset process? I’ve tried to rest it many many times, really very sad. Any experts can help please

[GiveMeABreak]

This has nothing to do with the battery. This fault code is associated with the DeNox system.

Without the full part of the code (you have 2 numbers of the code missing from the end) that a generic scanner probably won't be able to retrieve, I can't advise of what the specific fault is, but if the missing numbers are 21, then it relates to the UREA pressure.

[kenykl]

I used a OBD code reader to check it out, it is P20E8$07e8, the code for another c4 Picasso owner changed the same battery. I tried to erase the code by using the OBD reader, it can erase the code but the code back about 20 mins later. No idea what to do next. I think the OBD reader is not comparable with Digabox, what should I tell garage people about what to do next please? Thank you.

[GiveMeABreak]

Well of course the code will come back - you can't magically erase it, so you will need to correct the underlying issue or it will just remain. The code you have supplied is missing some part to it and it's not what you have added on after in your last post. It will be 7 alphanumeric characters in length, so P20E8 21 for example.

Without the last bit I can't help you as there are literally hundreds of fault codes for the engine management system. The last 2 digits will narrow the fault down. If you are using Diagbox it will give you the proper code assuming you are using a proper VCI to connect and not a generic OBD reader as that won't work.