Temp Guage/Sensor Topic is solved

[ahacking]

I have a 2004 S80T6. I just replaced the head gasket and it runs great. The issue is that my temp sensor was working before the head gasket job and now I am having issues. I get no reading then if I accelerate hard I get a reading (normal temp) then it stops when I shut off the car. It goes from 0 to mid temp and no where in between.

I replaced the thermostat but not the sensor.

Troubleshooting
I have determined the resistance of the old currently installed sensor is 600ohms when hot.
I have 5V coming from the ECU to the sensor.
I have a new sensor, so I dropped it in hot water and connected it to the temp sensor plug, no reading at room temp (measured 1900 ohms), or in hot water (800 ohms)

I'm wondering if this is an issue somewhere else and where to go from here?

[jimmy57]

Get a paper clip and set it on the anvil part of a vise or other metal surface suitable for hammering metal flat. Flatten the paper clip on the end for 1/2 inch to be the approximate thickness of those pins you see down in sensor connector. Use that end to insert into the connector on harness for the sensor to see if one of the pins is loose. The terminals can lose their shape and not make connection much like when one of your wall outlets gets worn and the lamp cord has to be just so or the map doesn't work. If one is loose then you might be able to bend sides inward with one of those very fine jeweler's picks or eyeglass screwdriver to get to have better contact tension. The sensor should read close to 200 ohms at boiling temp.

[ahacking]

Thanks. Will try.

[oragex]

Besides the above (those wires also crack near the connector as well), I'm thinking there is an air bubble trapped inside the housing. Not sure if technically is possible, but that would explain a switch from 0 to 12 under heavy acceleration. Just a guess