O2 sensor EML after refuelling...?

[Deev]

I know it's a popular sport here to post ODB2 codes and hope for the best, but mine appears to have a weird coincidence - or is it a coincidence...?

Anyway - in the 3 and a bit years I've had my Leon 1.4 FR (non-ACT), I've had the EML appear 3 times - The first time I cleared it and it didn't reappear for the best part of a year. Now interestingly the second time it appeared, it cleared itself the next day (so I can't actually confirm it's the same code as I didn't have time to check!). The third time it happened was just before Christmas. Both times I managed to read it, the code was P219600: O2 Sensor Signal Stuck Rich Bank 1 Sensor 1

Now, what I find weird is, every time the code has happened, it has happened shortly after I have refuelled - or, as far as I can tell, as soon as I've "opened the taps" (i.e. got to a decent speed) after refuelling. Now, I did suspect it may be just crappy cheap fuel (I always try to put decent fuel in and never go anywhere near supermarket crap) but the first two times I was away from home and didn't have a lot of options, first time was "Applegreen" (who?) and the second time was Jet. However that theory dissolved away a little this time as I'd just filled up with Esso...

What do we think? Coincidence, or might I be on to something?

Anyway - I've just cleared the code again and it's staying off for now. If it's only appearing once a year I'm not going to panic... yet...!

 

[cupra14]

It's not the fuel. That all meets a standard by law.

Yes, coincidence.

If you clear a code like that one it will also clear the OBD monitors and until they manage to set again (and unusually they may not) lots of codes cannot flag. So, best not to clear. You're only supposed to clear after a fix.

And no need to clear anyway as they self-clear if the fault has gone for 4 warm ups.

You may have a failing O2 sensor. They cope with a truly horrid environment remarkably well but ... they basically have a life and die.

 

[Deev]

Fair enough. I know I cleared the code the first time it happened because the general consensus was to clear a "first time" code in case it's just an anomaly. Given this is happening so infrequently I cleared this time as it's evidently something very borderline. I did think that possibly a dodgy sensor and that a change of fuel mixture is right on the edge of limits. I wonder if it's worth keeping the ODB dongle plugged in and see if I can (work out how to!) log the suspect sensor whilst driving - although I guess that would also require knowing what the normal parameters actually are!

Looking at the other possible causes of that fault code (vacuum leak, injectors etc), I'm more inclined to believe it's an actual sensor fault, as the drive isn't affected at all, and I would have thought those issues would have caused actual, noticeable symptoms whilst driving (as opposed to just an angry warning light!).

Anyway, it's service and MoT time in a few weeks so I'll mention my findings to the garage and perhaps just ask them to change the sensor (considered doing it myself but apparently it's a bit of a PITA to access on this engine so I'd rather not make a ham fisted attempt and end up causing more problems).

 

[cupra14]

To check for an air (vacuum) leak, get engine hot then park & look at fuel trims at idle. If well away from zero something is amiss. If you then rev to 2500 or so and the trims go much nearer zero you have a leak.

 

[Deev]

Cheers - good advice - I'll give it a go