reinhardmoon5

Seat Formentor engine issues

Okay, I'm officially pulling my hair out! My 2020 Seat Formentor with a gasoline engine is giving me absolute fits. Got almost 171567 km on the clock. The engine light is on, the engine's running rough, and I'm getting this awful exhaust smell, like there's a leak somewhere. I suspect it is the lambda sensor. Any ideas? I did a quick scan with my OBD2 reader, and it's pointing towards "exhaust treatment malfunction", so I figured it must be something with the particulate filter or something to do with the oxygen sensor. Seriously frustrating!

A 2020 Seat Formentor with a gasoline engine and 171,567 km is experiencing engine issues, including a warning light, rough running, and an exhaust smell. The initial suspicion is a faulty lambda sensor, supported by an OBD2 scan indicating an "exhaust treatment malfunction." Suggestions include checking the NOx sensors and EGR valve, but ultimately, the lambda sensor is confirmed as the problem. Replacing the sensor resolves the issues, restoring smooth engine operation.

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4 comment(s)

Sounds like a familiar pain. I had a similar issue with my old Opel Astra a while back. Engine light, rough idle, the works. Have you checked your NOx sensors, besides the usual oxygen sensor? Those can throw a wrench in things too. Also, how's the EGR valve looking?

Thanks for the quick reply! NOx sensors, huh? I hadn't thought of those. Where exactly are they located, and how would I even check if they're faulty? And the EGR valve, is that something I can clean myself, or is it best left to the professionals?

The NOx sensors are usually somewhere around the catalytic converter. As for checking them, honestly, without proper diagnostic tools, it's tricky. You could try visually inspecting the EGR valve for carbon buildup, but cleaning it is a messy job and might not fix the problem. Honestly, with those symptoms, especially the exhaust smell, I'd bite the bullet and take it to a decent workshop. Probably something with the lambda sensor as you suspected.

Took your advice and brought it to the workshop. Turns out it WAS the lambda sensor, just like you suspected! New sensor installed, and the error is gone. Cost me 375€, but at least the Formentor is running smoothly again. Thanks so much for your help, seriously!

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SEAT

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FORMENTOR