UK-POLOS.NET - THE VW Polo Forum

Hi new member here!

Just wondering if any of you guys can help. Recently I've had the engine management light on, after taking it to the garage they advised that there was an issues with the O2 sensor Bank 1 Sensor 2, I believe this is underneath the car?

The sensor had been changed last year as the same fault was showing, this did not fix it, last week a separate garage advised they tried put a new one in but this didn't fix this issue, so have put the old one back in and not charged. They suspect that it may be something to do with faulty wiring. Do any of you guys know whether this is a common problem, how to fix this and how much of a job it is.

Any help would be greatly appreciated

Volkswagen Polo 1.2 S A/C 2011


Cheers!

I'm not sure if that S2 Lambda sensor has a heater built into it, if so, maybe check fuses as if its heater fuse has blown then it would have issues.

From what I've seen on a much earlier 1.4 16V Polo 9N, the connection for that sensor is inside a plastic box underneath the car, so the "car side" of the wiring should be well protected, but maybe see if you can find any damaged cables in the engine bay.

I have just ran it through my diagnostic and have the following fault codes:

It could be that the heater for either probe has developed a fault and/or blown the fuse, so just replacing a probe will do nothing, or even the wiring has been damaged and has blown the fuse or fuses.

Maybe buy a Haynes workshop manual as that should have the wiring diagrams for that engine - and that would help you find the related fuse, and see if its gone, replace it to see if it blows again as that is a cheap thing to do, then take it from there.

Edit:- probe sensor 1 bank 1 is the precat control Lambda sensor, probe sensor 2 bank 1 is the emissions monitoring/warning probe. Your car only has one cylinder bank so that is why it gets called bank 1.

On second thoughts, ignore buying a Haynes manual to find out these fuses, that info is not in it!

So, make a list of all your car's fuses positions and values including any under the dashboard away from the main fuse board and include all the fuses under the bonnet in a few areas.

Then buy some same value/type of fuses for replacing any/all blown fuses, follow this by removing every fuse one at a time and check it closely visually to make sure that each one is okay or blown, replacing every blown fuse with a same value new fuse.

After that, note down all logged faults then clear them and run the engine - and take it from there, if a fuse blows again, note its number and unplug the S1 and S2 probes and replace the newly blown fuses, use logic to find out if it is a Lambda sensor that is blowing that/these fuses or the wiring harness, then if it is a Lambda sensor find out which using the same method, buy a replacement part made only by NTK and fit it, if it is the wiring harness get it repaired or fix it yourself.

Buying cheap Lambda sensors can turn out to be expensive as these car systems seem to be very sensitive to which brand of sensor you buy.

Thanks for your help!

I've just checked all the fuses under the steering wheel and they all look to be fine, which is frustrating as I hoped it would be a quick win!

I suspect it's something between the sensor and the fuse that is causing the issue. Possibly some deterioration of wiring?

I'd hope a bit early in its life for that, but you never know.

I'd think that you will need to check every fuse location in that car, I think that there might even be a "fuse map" for your 6R Polo on this forum, maybe have a good look around.

According to the following:

https://drive.google.com/open?id=0BxYPV ... m56Y19tOE0

The lambda sensors should be house in either fuse 8 or 28. Mine doesn't seem to have a fuse in either...

I've now put a 10a fuse in socket 28 and am receiving the following fault codes, no engine management light after 3 startups.

Any further advice?

Bother, so now you have found a "fuse map" and it does not tie in with how things are in your car, not very handy! As far as that info is concerned, FS8 is for the injectors and you don't have one fitted in that slot so the engine can not run, very annoying, keep trying for other info on fuses for the 6R.

I think that VW were aware about this lack of consistent correct info and in the owner's handbook said "ask at your dealership"!

It looks to have rectified the Sensor 2 issues, so I'm wondering whether it may be an issue with the Sensor 1 upstream sensor.

I may have a look tonight, do you know exactly where it is located?

It could well be visible under the bonnet, sticking out from the manu-cat.