16500 - Engine Coolant Temp. Sensor (G62): Implausible Signal

[SkipFeeney]

Hi All,

Got a 1.8 1999 Passat that is running roug. I did a check on VCDS lite and got the following error - 16500 - Engine Coolant Temp. Sensor (G62): Implausible Signal

Yesterday I replaced the sensor with a new one (blue - square 4 pin) and cleared the code. Took it for a 20 min drive and the code didn't come back. However today I have been on a 2 hour trip and the code has re-appeared. Any ideas what it could be?

Thanks

[Crasher]

Monitor the signal from the sensor in measuring blocks on a long drive and see if the temperature goes from hot when standing still and then cools considerably whilst driving. If it does, you have a faulty/missing thermostat.

[SkipFeeney]

Monitor the signal from the sensor in measuring blocks on a long drive and see if the temperature goes from hot when standing still and then cools considerably whilst driving. If it does, you have a faulty/missing thermostat.

Dumb question...is the faulty / missing thermostat different to the engine coolant sensor?!

[SkipFeeney]

Dumb question...is the faulty / missing thermostat different to the engine coolant sensor?!

Just taken it for a 20 min drive and it does display the symptoms you mentioned. When driving the temp gauge seems to stay under 70, i then parked up and left it idling and it went to 90. Then when i set off it went back to 70 - is this not normal then? I also noticed on a long motorway drive the temp stays around 70 - i just assumed enough air was going to the engine to cool it?

[Crasher]

Fit a new thermostat, if you don't know the difference between a coolant temperature sender and a thermostat I begin to worry, even my wife worked that one out!

This is a thermostat



On an ADR engine the thermostat is under the black plastic cover at the end of the hose with two 10-mm headed M5 hex head set screws.

[SkipFeeney]

Lol thanks Crasher - I have to start somewhere

Tonight i removed the thermostat and attempted to fit a new one, however I can't get it or the O ring to stay in place long enough to get the hose back on and the bolts fastened!

Is there a trick to it?