O2 exhaust sensor

[Jovin]

Hi All
Yesterday my engine light came on indicating an exhaust o2 sensor problem which I was able to confirm with Carista (cant remember code). I reset it and just done a 30 mile trip and it's not come back on. Do these things become intermittent and if so once the fault has been registered by the vehicle would the warning light stay on even if the sensor started working again? There was no mis-fire or lack of power, fuel consumption seems normal and idle was steady.
Vehicle is 2018 Leon ST FR 1.4 ACT 150bhp.

Many thanks.

 

[mcspook]

When the ECU log a fault, depending on the fault, it's logging it first, and if the fault continue then it shows a warning light. The warning light stays on until you reset the fault. If the light come again for the same reason then you probably need an o2 sensor or something else that has to do with the o2 sensor reading. Most common o2 problem I know of, is the internal heater of the o2 sensor failing.

 

[RUM4MO]

Yes I agree that it will probably be the S1 or precat sensor and typically a heater failure being detected. Initially they tend to be intermittent and far apart time/miles wise, and increasing in frequency.
Normally, the fault condition will occur and that will latch the Exhaust Emissions warning light, when it stops being a fault, the warning light will stay on for "so many" engine starts and then it will get switched off, although the fault code is typically held in engine ECU memory until cleared by a scan tool or the battery temporarily disconnected.
Certainly in the past VW Group only ever fitted NTK Lambda sensors, and if you buy a VW Group replacement it will normally be an NTK branded item with VW Group ident on it. I've only ever replaced one many many years ago and I could not buy an NTK branded aftermarket one and get it on my doorstep any cheaper than I could buy it from my local VW Group dealership - but maybe things have changed, maybe requesting a price from independent providers of genuine VW Group parts, like CCP - ie Coverdale Car Parts, will get you it at a sensible price, you will only find that out by contacting them for a price. Buying any/all other suppliers parts for this job tends to only fix this problem for a shortish time, which might be okay if you are just about to move this car on, but better to stick with NTK either as an aftermarket brand or a genuine VW Group part.