Viano engine stalls at idle fuel composition error

Incorrect fuel composition errors can be tricky. It’s possible that wrong fuel or fuel additives are the issue, but you'd likely notice performance issues across the rev range, not just at idle. Fuel contamination is certainly a possibility, and that contamination could partially clog the fuel filter, restricting fuel flow at low engine speeds. However, before assuming the worst, have you checked the basics like the fuel injectors? Defective cable or plug connections can also trigger that fault. Also, what specific error code are you seeing? Knowing the exact code can give us a much clearer picture.

Thanks for the quick reply! I haven't checked the fuel injectors myself, honestly, that's a bit beyond my comfort zone. I also didn't think about the cable or plug connections - is that something I can easily check myself, or am I better off taking it to a professional? As for the exact error code, I'll have to check again, but where would I even begin to look for a defective cable or plug?

Given the stalling issue at idle and the error code pointing to fuel composition, it's best not to throw parts at it. I'd suggest taking your Viano to a workshop. The error memory will provide the mechanics a fault code, and the error code will pinpoint the exact location of the issue. The fact that they suspect a 'cable or plug connection of the component defective' suggests the diagnostic pointed them to a specific area. A proper diagnosis will likely save you money in the long run. 95€ seems reasonable for fixing a dodgy connection.

You were spot on! I took it to the shop, and they found a loose connection on one of the fuel composition sensors. 95€ later, and the Viano is running perfectly again. No more check engine light, and the idle is smooth as butter. Thanks again for the advice!