Peugeot 106 exhaust treatment malfunction

I had something similar happen on my 106, although I didn't run diagnostics myself. When the engine light came on I noticed a rough idle and a strong smell of exhaust. If your exhaust is actually leaking then that would definitely impact the oxygen sensor readings, causing it to throw a fault. I also had some hesitation when accelerating. Was this a consistent problem, or was it only occasional?

Thanks for the reply! It's pretty consistent now, unfortunately. The rough running is there most of the time, and the smell is always present. The engine light stays on constantly. Did you also suspect the lambda sensor, and if so, what steps did you take to confirm?

I did initially suspect the lambda sensor because that's a common issue, and I had read a lot about the particulate filter and NOx sensors as well. However, given the exhaust leak and the consistency of the problem, it really needs a professional diagnosis. I took mine to a trusted workshop and they confirmed the lambda sensor failure, which they attributed to the exhaust leak. They found some corrosion around the exhaust manifold gasket which they had to replace before swapping the sensor.

Okay, sounds like I'm on the right track, but a workshop visit is definitely in order. Thanks for sharing your experience! Turns out it was the lambda sensor, as suspected. The workshop also found a small exhaust leak near the manifold, just like you mentioned. Total repair cost was 375€, including parts and labor. Running much better now!