Checking coolant temperature sensor

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Dec 6, 2007 | 09:25 AM

kgardnez

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Checking coolant temperature sensor

Does anyone have a feeling for the various gauge positions on the temp gauge in the car vs. coolant temp?

I would like to heat up water to various temps and check if my coolant sensor is working right.

Dec 6, 2007 | 09:32 AM

quattro_blue

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Vag-com can tell you exact coolant temperature.

Dec 6, 2007 | 09:55 AM

kgardnez

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Vag-com tells you what the sensor sees... I suppose I could use that. Which sensor does it read?

Dec 6, 2007 | 11:33 AM

Vier GlÃ¼hende Ringe

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The sensor is really cheap, just replace it, or if you are stubborn, watch MVB 1 with VAG-COM...

as the car warms up. If it jumps around more than 3 or 4 degrees then it is bad. Also if you go to 17 instrument cluster you can do a gauge sweep.

Dec 6, 2007 | 01:10 PM

David.Norton

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Keep in mind that it is two sensors...

one drives the gauge, the second the ECU, hence the three terminals. So you can have a problem gauge, but the engine runs fine, or the reverse. Why they did this I can't begin to guess.

Dec 6, 2007 | 01:39 PM

kgardnez

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Sorry, do you mean two seperate sensors or 2 sensors in the one green housing?

Dec 6, 2007 | 04:17 PM

kgardnez

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Checked with Vag-com tonight, is this how a bad sensor acts?

Warm up the car in my driveway to 78C, when I drive slowly down the street it drops a couple of degree, drive 1/4 mile down the main road and it's dropped to < 70C. Pull back in the sub and into the driveway and I seem +/- 1-2C fluctuations, but it rises to 78C again.

Outside temp is -5C

Vag-com numbers match with the gauge.