Peugeot 408 uneven idling

I had a similar issue with my 408. The idling was rough, and the error codes pointed towards the engine mount. Have you checked the transmission mount as well? Sometimes, a failure there can mimic engine mount symptoms. It's worth a look before you start replacing parts.

Thanks for the response. That's a good point about the transmission mount. I haven't specifically checked it. Could you elaborate on how the transmission mount issue presented itself in your case? Was it also accompanied by a stored error, or were there any other noticeable symptoms besides the uneven idling?

Yes, the error code was the same. To be honest, I am not 100% sure, but my mechanic said that the rubber mount was cracked. You should probably get it checked in a workshop.

I appreciate the advice! I will take it to a workshop for a thorough inspection, specifically focusing on both the engine and transmission mounts, as well as the cable and plug connections. Thanks again for sharing your experience; it's been very helpful in guiding my next steps. It will cost me around 95€.