Temp Gauge at half all the time
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Temp Gauge at half all the time
I had a issue with my civic overheating over the weekend. Turned out to be a stuck thermastat which I have fixed. The problem that I'm having now is that the temp gauge is reading just above half now all the time. The car sat for 2 days, went to start it, just over half right away. Drive it anywhere. Just over half. Turn the car off, temp indicator goes to the bottom. Turn it on just over half. The car is not showing any codes. Anyone with ideas???
If you think a good mechanic is expensive, try hiring a bad one
Joined: Dec 2011
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From: Midwest. Aiming about mid-chest
Rep Power: 518 
Re: Temp Gauge at half all the time
CEL on? Troubleshoot the check engine light first.
Plug a scanner in and read the coolant temp that the computer sees.
If the PCM reads the wrong coolant temp, then unplug the sensor and see it if reads -40F. (It should.) Probably replace the sensor for being inaccurate. (The engine would probably run poorly too.)
If no joy,
Next is troubleshoot the multiplex unit for codes.
Then do a self test on the gauge cluster.
See if the needle makes a full sweep during the self test, and see if any relevant info is revealed during the self tests.
The how-tos should all be in a good service manual.
Try a reset: disconnect the battery cables and hold them together for at least one minute. Reconnect and see what happens. (Don't forget to do an idle relearn.)
The cluster relies on data from the PCM to operate the gauges. If nothing above got you any answers, then it's either the PCM or the cluster.
HTH
Plug a scanner in and read the coolant temp that the computer sees.
If the PCM reads the wrong coolant temp, then unplug the sensor and see it if reads -40F. (It should.) Probably replace the sensor for being inaccurate. (The engine would probably run poorly too.)
If no joy,
Next is troubleshoot the multiplex unit for codes.
Then do a self test on the gauge cluster.
See if the needle makes a full sweep during the self test, and see if any relevant info is revealed during the self tests.
The how-tos should all be in a good service manual.
Try a reset: disconnect the battery cables and hold them together for at least one minute. Reconnect and see what happens. (Don't forget to do an idle relearn.)
The cluster relies on data from the PCM to operate the gauges. If nothing above got you any answers, then it's either the PCM or the cluster.
HTH
If you think a good mechanic is expensive, try hiring a bad one
Joined: Dec 2011
Posts: 32,017
Likes: 256
From: Midwest. Aiming about mid-chest
Rep Power: 518 Re: Temp Gauge at half all the time
What does the temp read in the datalist when the engine is stone cold? Sitting overnight should leave the IAT and the ECT reading within just a couple degrees of each other (and ambient temp) before running the engine---easy check.
This should tell you if the sensor is accurate or not.
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Finally got around to replacing the sensor today. Everything is fine now. I found that the sensor had a crack in it at the top. When that sensor is gone it even makes the car extreamly hard to start, but if you disconnect it, the car will start fine. Thanks for the input.
Glad we could help, even though it seems you had it all under control. 
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