O2 Sensor No1 No Reading on OBD Scanner

[lenny penne]

Hi all, new to the board and new to Polo ownership but had plenty of VWs, Audis and Seats in the past.

I've recently bought a 2003 1.2 Polo E to use for the daily commute. I got it cheap because it was running out of MOT and the MIL light was lit, no problem I thought. Connected up my scanner and it showed P0031 and P0037 so I checked the wiring first and found the first O2 sensor had rubbed on the exhaust manifold and had melted the plastic coating revealing the grey and yellow wires which had shorted against each other. I repaired this and replaced the second post-cat sensor which was in a right state. I cleared the codes and took it for a test drive, upon restarting the codes lit up again, on checking sensor 1 shows no readings on my scanner but sensor 2 seems to be reading ok.

I'm presuming the feed for the sensor heating comes from the ECU as I can't find any fuses for it or am I wrong?

Any tips on what I should be looking for please?

Thanks in advance,

John

[RUM4MO]

Hello there and welcome to this forum!

I suspect that there is a heater circuit fuse for at least the front Lambda sensor, but never having needed to find out which one, I can't say more, have you, or have you ever considered buying a Haynes manual for this car, it could end up being quite useful for a car at this age and for this sort of problem.

The description of the areas covered by that fuse could be quite vague from cloudy memory!

So check all fuses that you can find - in the main fuse box, maybe under the steering wheel area and maybe under the bonnet.

[lenny penne]

Thanks for that, it took me all day but managed to trace the fault to the wiring harness where the O2 sensor plugs in. Someone had put a new plug on and just taped the connections together resulting in another short which had blown fuse No 9.

Replaced everything, cleared the codes and put it in for it's MOT this afternoon which it only failed on a worn suspension bush so a result of sorts

[RUM4MO]

Messy beggars!

Still for you - progress!