Cima Engine Light and Exhaust Smell

Interesting. I've got a Cima too, and I had almost the exact same symptoms a while back – engine light, rough running, and a nasty exhaust smell. Honestly, it could be a few things. Have you checked for any obvious exhaust leaks? Maybe around the manifold or the catalytic converter? Also, are you sure it's not something like a blocked EGR valve causing the rough running and triggering the light? I'm just throwing some ideas out there, but it could also be a faulty oxygen sensor as you suggested.

Thanks for the reply! I did a quick visual check for exhaust leaks and didn't see anything obvious, but I'll definitely take a closer look around the manifold and catalytic converter. As for the EGR valve, I haven't checked that yet. Is there an easy way to diagnose a blocked EGR valve without taking everything apart? And if it is the oxygen sensor, is there a way to confirm that before replacing it? I'd hate to just throw parts at it without knowing for sure.

Visual checks can be deceiving with exhaust leaks; sometimes they're small cracks that are hard to spot without a proper smoke test. Regarding the EGR valve, you can sometimes tell if it's stuck open by tapping on it lightly while the engine is running. If the idle changes, that might indicate it's stuck. As for the oxygen sensor, ideally, you'd want to check its readings with an OBD-II scanner to see if it's fluctuating properly. If it's flatlining or giving consistently wrong readings, that's a pretty good sign it's the culprit. But honestly, with all those symptoms combined, and especially the exhaust leak smell, I'd recommend taking it to a reputable workshop. They can do a proper diagnosis and pinpoint the exact problem before you start spending money on parts.

Thanks a bunch for the advice! I think you're right, I'm probably better off taking it to a workshop to get a proper diagnosis. I was hoping to avoid the expense, but it sounds like there are too many possibilities to just start guessing. For future reference and closure, I took it to the shop, and you were spot on with the oxygen sensor! It was defective, causing the engine to run rough and throwing off the exhaust readings, leading to the leak smell. The repair cost me about 375€ including the new sensor and labor. Thanks again for pointing me in the right direction!