Peugeot 508 transmission issue

Whoa, that sounds familiar! I had something similar happen in my 508. The transmission was acting all kinds of crazy. Lights flashing, weird shifting... it was a nightmare! Did you check for any coolant leaks? Maybe the oil cooler is going bad and messing with the whole cooling system? Or perhaps the cooling fan isn't kicking in like it should. Could be a simple radiator repair, but honestly, those symptoms sound like more than just that.

Coolant leaks, huh? I haven't noticed anything obvious, but where exactly should I be looking? And how would that relate to the radiator oil pressure error? Just trying to get a better handle on this before I take it in.

Yeah, coolant could be leaking from a number of places, especially around the oil cooler if that's the problem. Honestly, the way your transmission is behaving points to something messing with the oil pressure. Could be a bad sensor, but with all those symptoms, I'd get it to a workshop ASAP. It sounds like a bigger issue than a simple fix. It is probably just a defective cable or plug connection as you suggested. My issue ended up being a corroded connector to the transmission control module. Good luck!

Thanks a lot for the insight! I took it to the workshop, and you were right – it was a defective cable/plug connection, like the error code suggested. They replaced the cable and everything is back to normal. Repair cost was 95€. Really appreciate the help!