Hello, the problem I'm having is. While driving along my temperature guage will stop working and display __ __ __ . When this happens the A/C quits working and the check engine light is illuminated. The blower is still blowing but the compressor is not working. After 15 or 20 minutes the guage will come back online and the A/C will again blow cold. I hooked up my Scan-tron and there is only one generic code displayed. Code #P0128 I have seen a couple of other people have the same problem and they were able to fix it by changing the coolant temperature sensor and thermostat. I replaced the temp sensor and everything worked great. Got in this morning and its doing the same thing again. If anyone could please help I would greatly appreciate it. Thank you very much

 

Welcome to the forum. Between P0128, ECT sensor, and thermostat, you replaced the ECT sensor. I think you just answered your own question.

 

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EinST makes a good point. The thermostat may be the second part of the equation.

Keep us posted.

Louis
GM Customer Service

 

Thank you both for taking the time to reply to my post, I really appreciate the help. I am going to change the thermostat this evening and I will post the results. I am so glad I found this forum. Tons of useful information from fellow Chevrolet owners, fans and technicians. Thanks again

 

Resurrecting an old post.



Was the thermostat the problem?


Why would a stuck open thermostat cause the flatline readout on the dash status readout? I just changed my temp sending unit, to no avail. Next will be the thermostat, but why? Seems like it would show coolant warming up to something below 180, rather than not work at all.


Recently flushed the radiator fluid. Could there be an air pocket at the sending unit, causing it to not have fluid against it and not able to read any temperature? I noticed nothing poured out when I replaced the sending unit.


Thanks in advance for any ideas.


Long Range


Update:


Changed the thermostat, no help. So I started messing with the wiring loom under the hood and everything (including AC) started working. I must have a short in the wiring.

 

@Long_Range:

I had the same issue of the coolant temperature reading "---". I also changed the thermostat and it didn't fix the problem.

I ended up changing the coolant temperature sensor (located just behind the thermostat housing) and it fixed my issue. It is a 5 minute fix for around $20. You just have to be fast enough to switch the old sensor out with the new one, or it will drain coolant. If you set yourself to swap quickly, you should lose more than a spoonful.

You need a 19mm deep well socket.
- Unclip the wire harness from the sensor, stuff it somewhere out of the way.
- Unscrew the sensor most of the way out of the hole, then position your new sensor close so you can plug the hole as soon as you pull the old one out.
- Tighten it down and clip the wire harness back in.
- After driving for a few miles, your computer should reset and your coolant temperature should read like normal.

BWD Engine Coolant Temperature Sender WT5132: Advance Auto Parts