For a few weeks now, when I start the car, after a few seconds, the temperature light comes on and beeps. If I wait a few minutes, turn off the engine and then restart it, the warning doesn't appear, and all is well. The gauge itself is also a little temperamental, rarely reaching mid way, and sometimes dropping off altogether.

I assume this is a sensor issue, the coolant level is fine, car runs fine, doesn't overheat.

Any pointers as to what to try first would be much appreciated.

Many thanks.

Cleaning the level probes in the coolant reservoir with a flat bladed screwdriver might fix the warning. It's quite a common problem.

 

The temperature gauge is likely a separate issue - probably the thermostat needs replacing. If replacing the thermostat doesn't fix it then try replacing the coolant temperature sensor too.

As above, I’d replace both the sensor and thermo. I’ve done this recently as the car would keep temp.

The gauge not hitting "89" is 100% CTS.

Buy a genuine one, VAG engines dont like After market sensors.

 

Clean the level probes as above, thatl sort the level warning 

@Regsmyth  Second to all the advice above. The level probes are obvious if you take the cover off the expansion tank with the engine cold.

2 hours ago, mac11irl said:

The gauge not hitting "89" is 100% CTS.

Buy a genuine one, VAG engines dont like After market sensors.

 

Clean the level probes as above, thatl sort the level warning 

 

Agreed to buy a genuine one, but disagree that it's 100% likely to be the CTS that's the cause of the problem. In my experience it was the thermostat, not the CTS that was the issue.

And in mine (and dozens of others here over my years) it was the CTS, as after i had a cambelt, pump and stat changed, mine still never went passed 70. Had a new CTS to go in, but never got around to it so i left it in the glovebox when i traded the old donkey in for someone else to look after.

The dash temp gauge gets its signal from the CTS, so when thats on the way out, signal degrades and reading goes wonky

Thanks all, I have "cleaned" the probes (they didn't look dirty), and the warning hasn't come on for a couple of journeys, so fingers crossed that's it.

The temp problem is probably the CTS, as sometimes the gauge drops right down, and then comes back up (particularly when car is hot). I don't think it would do that if it was the thermostat.

But my local VW specialist has quoted about £35 plus VAT for the CTS. I might just risk trying a cheap one, or a used one. Or just leave it (for now....).

 

Thanks again.

 

@Regsmyth

 

I ignored mine for 2yrs and it ran like a clock the whole time... 

 

1 hour ago, mac11irl said:

@Regsmyth

 

I ignored mine for 2yrs and it ran like a clock the whole time... 

Ditto, but I do wonder if the ECU ups the fueling if its told the engine isnt fully up to op temp ?

1 hour ago, mac11irl said:

 

 

3 hours ago, olddog said:

Ditto, but I do wonder if the ECU ups the fueling if its told the engine isnt fully up to op temp ?

 

 

If it did,i never noticed any real difference...

@Regsmyth - Well, I scraped the prongs on my level sensor years ago, and haven't had a false positive coolant warning since.

 

As for the CTS, that's an object lesson in "buy cheap, buy twice" (meaning one cheap one, and then a genuine one as well).

16 hours ago, mac11irl said:

 

I ignored mine for 2yrs and it ran like a clock the whole time... 

 

 

If you'd looked after it instead, it might have run like a temperature sensor instead...