P1AA2 c4 b78 1.6hdi problem solved

[Djandree]

Hello

I had a problem with my c4 b78 1.6hdi for a more than year. It was a weird one. After replacing old battery, new battery came with P1AA2 fault code in Voltage Retaining Device. Check engine pop out, Start/Stop went orange. But it was on and off. Some day Start/Stop worked (max time 30sec on the new battery), some day kick out straight away after switching on the engine. Description Voltage Retaining Device: Supply Open Circuit or Short Circuit To Earth. I didn't pay much more attention for a long time. But one day engine refused to start. I put battery on charging, after couple hours, I tried to start the engine and still nothing. Instead got rear wiper on, and alarm went on. Checked battery under the load, and battery was good. but the battery couldn't start up the engine. I started to check all connections, everything looked normal. I dig up on youtube a video from some bloke who had similar problem with his ds4.


I did it with my c4. There was a rusted earth connection going straight to Start/Stop system Main earth going from battery to Start/Stop system. After unscrewing a nut (need a laser tool 8614 tri lobe S/S capacitator socket psa group), I did a proper clean of this connection.. and Voilà ))) all faults disappear, Start/Stop working like a dream