My Grandad passed away recently and Im just in the process of selling his x-reg 1.6 16v megane.

It had a new post cat lambda sensor to get it through the MOT but the emissions fault light has now come back on again. I did a bit of research and found that there is also a pre cat lambda sensor which could be the fault. I replaced this today but the light is still on! I drove the car 200+ miles home 2 weeks ago with the light on and it runs perfectly.

Any ideas?

Car has only done 44k miles so surely the cat itself is still ok?

 

have you plugged it into a computer to check what the new code is that its found ?

 

i'm quite good with renault especially the F7R and F7P Engines give me a pm etc if you need some work doing

 

Bought an OBD2 scan tool for £20, showing O2 sensor faults, erased, 60miles happy motoring, problem solved!