UK-POLOS.NET - THE VW Polo Forum

Hi All,

I was wondering if anyone could point me in the right direction… I’ve had my first issue with the car in 3 years and over 130,000 miles.

My 2020 Polo AW GTi+ has been running the Revo performance pack / stage 2 perfectly for well over 100,000 miles now and I absolutely love it.

About 1 month ago the oil temperature sensor failed, giving the yellow oil can symbol to visit a workshop to replace the sensor and obviously giving no more oil temperature data on the dash.

The car has been into my local VAG specialist where they have gone through and replaced every oil temp & pressure sensor with genuine VW parts but it has not resolved the issue and its still giving error message - oil temp sensor faulty.

The car has also been diagnosed by an independent auto electrician who spent almost a full day investigating & checking all wiring, switches & terminals etc and advised that there appears to be an issue with the ECU and not any of the sensors.

The error code P0197 will not remove, despite their best efforts. I've been told this will likely require a replacement ECU.

Revo have advised that there's nothing they can do to help with looking at the ECU error codes etc and can't help any further.

Is there anything that can be done to permanently remove the P0197 error code and the yellow oil can symbol from the dash now all oil related sensors have been replaced?

I’m being told as this is an MOT failure, I have to scrap the car or break it for parts which is ridiculous. Apart from this issue the car is perfect, in amazing condition still and I’ve poured in thousands of pounds of mods and maintenance in the last few years.

Thanks in advance
Gav

Was the actual oil pressure checked with a pressure gauge?

On all my VWs from ~ year 2000 onwards, the oil pressure alarm is not enabled until the engine reaches somewhere around 1800/2000RPM, easy to test on a "healty" system, just remove the oil pressure sensor wire and start the engine, no alarm will annunciate until you rev the engine up, at least this test might narrow down the problem.

Thanks for the info John...

The oil pressure was not checked with an external gauge but my garage did replace all the oil temperature and pressure sensors while they were working around the engine doing their fault finding

i'll speak to the garage this week... As it stands just now, the oil temp sensor warning comes on about 30 seconds after engine startup and before the car moves or revs above 1800rpm

Was the correct part number installed?

GavinW wrote: Mon May 05, 2025 5:24 pm Thanks for the info John...

The oil pressure was not checked with an external gauge but my garage did replace all the oil temperature and pressure sensors while they were working around the engine doing their fault finding

i'll speak to the garage this week... As it stands just now, the oil temp sensor warning comes on about 30 seconds after engine startup and before the car moves or revs above 1800rpm

Got a mixed up between oil temp and oil pressure alarm!.
However, again, all my VWs from ~ year 2000 onwards will only indicate (temperature gauge) a fairly true coolant temperature (as per VCDS) from 50C to ~ 70/75C, the temperature gauge will then rise fairly rapidly (under normal driving) to indicate a constant 90C up to 107C, so under normal driving conditions you will never see the temperature gauge reading higher than 90C even when the radiator fan cuts in.

VCDS readings from 2019 Polo 65bhp
Coolant Temp
VCDS/Temperature Gauge (Deg C)
52 /52
53/55
56/58
58/62
60/65
63/69
64/72
66/74
68/78
69/82
71/84
73/86
74/88
75/89
75/89

Thanks for clarifying The car is going in again in 2 weeks for its next 10k service so I'll ask them to re-check everything again.

They did install all OEM VW temp & pressure sensors so I assume there would be only one part number that would fit each location. Maybe there could be more than one Oil Temp sensor that would fit and they have installed the wrong one. Do you know how I could verify the correct part number?

Because of the location of the oil temp sensor, it's a complete pain for them to get it out and replace it. There was a couple of hours of disassembly of bits from the top of the engine before they could unscrew it!

Parts (ETKA): https://uk-polos.net/viewtopic.php?p=466570#p466570