Laguna Exhaust Treatment Malfunction

I had a similar issue with my Laguna, albeit a slightly different engine. Check your lambda sensor. The malfunction, running rough and exhaust smell could be oxygen sensor related. What about the EGR valve or particulate filter?

Thanks. Where exactly is the lambda sensor located, and could a defective exhaust pipe also contribute to these symptoms in your opinion?

It's usually located on the exhaust manifold, before or after the catalytic converter. A bad exhaust pipe could contribute. However, given the check engine light and rough running, it really sounds like the sensor. I would suggest going to a workshop to be sure.

Thanks for the advice. Turns out it was indeed the lambda sensor as suspected. Replacement plus labour cost me 375€. Runs smoothly now.