Citroen C5 Aircross 2025 48V Hybrid – No Start After Engine Wash

[AUAutoOficina]

Hi everyone,

I have a 2025 Citroen C5 Aircross 1.2 48V mild hybrid in my workshop.

The problem started after another workshop pressure-washed the engine. The car started briefly, then stopped and wouldn’t start again.

We removed the 48V traction battery and found its electronic board burnt inside. We fitted another used battery with exactly the same part number, but the car still won’t start.

The P/R/N/D/M lights keep flashing, and the dashboard says “Put gearbox in P” and “Electric traction system fault”.

We’re getting U0291, U1109, U1149, U11A0, U12A0, U12A2 and U11DE. The BSI also shows B123B. Both the hybrid gearbox ECU and traction battery ECU are not communicating with our scanners.

We’ve checked the fuses and body grounds. The original scan also showed P10D9:47, an internal fault in the 48V alternator.

Has anyone dealt with something similar? Could the gearbox electronics or CAN network also have been damaged? And does a replacement 48V battery need coding or initialisation?

I’ve attached the original Autel diagnostic report from before the car arrived at our workshop.

Any help would be appreciated. Thanks!

[mickthemaverick]

Surely a 2025 car is still under warranty so should be taken to a main dealer to sort out. If there are costs involved then they should be met by the garage that was stupid enough to pressure wash a hybrid!! One has to wonder why they did that?

[Richard_C]

Stellantis recalled thousands of mhev cars earlier this year because of possible contact between the fuel and electrical systems in wet conditions like heavy rain. I doubt they designed it to be pressure washed. If you can find recall details it might give you some ideas.