On my 1.5tdci, I have an intermittently occurring p0138, it's only triggered once so far in me owning the car, and that was today after driving through a flooded road (water level up to just above the bottom of my number) I drove through dead slow. Got to the tyre place (my destination) stopped, turned the car off, it was off for maybe a minute then turned it on to find a eml, got home, plugged my laptops in found the code, decided to read the live data, nothing looked unusual, reset the code then did a key on engine on self test and it didn't come back. Any help would be appreciated.

5 minutes ago, Neb_engineer said:

after driving through a flooded road

My thoughts would be that the Heated O₂ sensor was unhappy at getting very wet. Personally I'd do nothing unless the problem comes back.

Ah ok, just concerned as I have an MOT tomorrow morning and my only route is through the same slightly flooded road

18 hours ago, unofix said:

My thoughts would be that the Heated O₂ sensor was unhappy at getting very wet. Personally I'd do nothing unless the problem comes back.

Found the problem, the previous owner left the plug dangling (connected but not on the plastic mount) so the wire must have either a braided or melted on the exhaust leaving bare wire. Replaced the sensor so fingers crossed.

A very good find 👍

Hopefully that will be an end to that problem.

1 hour ago, unofix said:

A very good find 👍

Hopefully that will be an end to that problem.

Indeed, fingers crossed on the mot