Help With Fault Codes Please

[dirtbiker]

Hi All,

Firstly; the car is a Seat Leon 1.6s with the 16v AZD engine. I had some troubles with a failed flexible section in the exhaust so replaced the downpipe and cat-converter in January this year. Shortly after one of the timing belt tensioners failed so a new timing belt and tensioners was fitted.

The car's been driving fine ever since, no drop in fuel economy and passed the emissions on the MOT no problem at all.

But I've got a couple of fault codes coming up on my reader that don't seem to be causing any trouble but are tripping the CEL so I want them sorted out if possible!

17604 - Oxygen (Lambda) Sensor Heater Circuit: B1 S1: Electrical Malfunction
17591 - Linear O2 Sensor / Reference Voltage Short to B+

I've had a go at clearing them but they come back straight away so it's obviously a persistant fault.

I'm thinking that I'm going to have to replace the lambda sensor (behind the cat)? Any ideas other than this as I'm a bit reluctant to shell out £120 odd for the new sensor

 

[Big_daddy]

B1 is one before the Cat, check the wiring is not damage, must have got part damage when it was transfered over.

 

[dirtbiker]

I was beginning to think that might be the case (having spent a fair while under the car fiddling with the post cat sensor!)

I'll whip it out tomorrow and check/clean it and see if that helps. Thanks!

 

[RUM4MO]

Apart from checking over the lead and its plug/socket arrangement - check to see if the connector pins are clean and shiny, I'd expect that this problem is internal with the sensor and it happens quite a lot. Strange thing was for me with my wife's Polo 9N 1.4 16V BBY, when I went to buy a new probe the VW parts man was amazed that it would need replacing and it had to be ordered in - looking on some of these forums it seems to fail on quite a few cars! It is the probe heater that has failed I'd reckon and cleaning it will just make it worse if anything as the sensor along with the heater are inside a cage. I think that you should just buy from a main VAG dealer as the correct NGK (NTK) sensor is just as cheap from them as it is from proper on-line shops when you add P&P - I've checked that already and don't even consider "fit all" ones!

I'm not too certain about the second code number but the description sounds correct for this sort of probe failure and sounds a bit like the description that my other logged fault was for a failed probe.

BTW its B1 S1 that is pre-cat and B1 S2 that is post-cat the "B" in VAG speak is engine cylinder bank - and your engine only has one cylinder bank and that is B1 - a Vee engine would have B1 and B2.

I've had a look at code listings and I think that your second code has been "written" wrong it should be 17591 and not 17691, that would tie it in nicely with the description!

 

[dirtbiker]

Cheers RUM4MO, I'm hoping it's just a bad connection but from what I've read and what you've posted I suspect that the heater coil has failed inside the probe, we shall see!

You're correct, the code was written down wrong (not sure how I managed that one!). Now edited in the first post.

Many thanks

 

[dirtbiker]

A replacement lambda sensor (at £135 from the VW Dealer, ouch!) seems to have solved the problem. I've only done a few miles so far but the light was tripping on in the first few seconds of running so I think it's fine, fingers crossed!

Thanks for the advice people