Lambda sensor error

[audi321]

Hi all. My sons 2016 Twingo has the EML on and when I read the codes it s coming back as a lambda sensor error. I can clear the code and the EML goes off but returns after approx 30 mins of driving.

Some questions for those who know significantly more than I do.

1. After dismantling to find them, I see 2 sensors (1 pre and post cat). I don t know which one is at fault as the reader I have doesn t tell me (launch 123). But is it likely to be the one before the cat?

2. It is likely to be the sensor itself or is there a bigger chance something else is wrong and there genuinely is a problem with the exhaust gases? ie do these sensors fail very often? The mpg is normal and it recently passed mot without any issue. Although it since has developed a hole in the exhaust back box

3. Not the best option I know but is there a hack to stop these altogether? ie code them out permanently or simply leave the connectors undone? He won t have the car much longer.

Or any other option?

Thanks all for any advice.

[paul_c123]

Would be worth fixing the back box then seeing if it cures the issue - it can mess up the validity of the reading the sensor takes, and the ECU interprets this as the fault you have.

I mean, you're planning to fix the exhaust anyway, right??

[audi321]

Ah right. I’d not thought of the 2 being connected. Yes back box will be replaced anyways but it would have been nice to fix this all together whilst it’s apart (engine in boot).

I’ll replace the back box and see what happens with the EML.

Thanks for the help

[stevieturbo]

Any proper scan tool will tell you which one.

If unsure, unplug the sensor to force a fault.