Sitting in a car park last night engine running, thought it was getting a bit chilly, so turned the lights on the see the heater controls, looks at the engine temperature gauge and it was right around to 100 degrees if not a tiny bit more, I've noticed that it occasionally does that and creeps over well over the middle 90. Turned the heaters on full whack and it cooled down back to normal.

Is this this a common thing? Sensor, or something similar. The fan seems to kick in at different times on here for some reason? Sometimes it seems to kick in at 90, other times it waits until it gets right over 90 before it comes on. Any ideas?

Nackered fan switch maybe?

Sound like a dodgy sensor can you fault scan it?

Fault code read last night, nothing comes up what so ever, tried on a couple of machines too, a cheap code reader, then a proper snap on one. Only code that comes up occasionally is a P0171 which is a lean running on bank 1.

Edited 20 January, 201313 yr by DKB69

A few things possibly...bad temp sensor/thermostat/water pump impeller gone?

Coolant temp sensor which only causes the ECU to throw a code if it goes open circuit or intermittent. One of the the most common failures on Golf mkiv derived VAG cars. Replace with genuine VAG CTS only. Easy 5 min job.

Edited 20 January, 201313 yr by pauldazzle