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2009 Chevrolet Malibu temp gauge turns off

Ray, hi my name is Josh my wife owns a 2009 Chevy Malibu LTZ we have recently installed an after market coolant temp sensor and the temp guage continues to turn off. I have since changed the t-stat and still the temp guage turns off. I have topped off the coolant and there seems to be no loss what so ever. my question for you is do you think a coolant flush would fix the problem? thank you.

You are not actually asking Ray a question but a group of forum regulars who offer advice.

That said, Im not sure if I understand your problem. What do you mean by the “the temp gauge turns on and off”? As well as “installed an aftermarket coolant temp sensor”?

Did you install an aftermarket gauge and temp sensor? Or replace the factory temp sensor with an exact replacement made by an aftermarket supplier? Why did you do that? Is the car overheating? Or do you think it is overheating because either the car’s temp gauge or the aftermarket gauge jumps to the red?

You say you aren’t loosing coolant? Good! Since I don’t understand the problem, I can’t say a coolant flush would solve things. Post back and answer the questions and explain what is happening a little more and we’ll try and help.

ok. I see. The temp gauge is fine i purchased an exact temp sensor from an after market distributor. The car does not read the temperature at times so i use an obd2 scan tool to erase pending codes and then the guage continues to display the temperature of the vehicle. The car does not overheat to my knowledge it doesnt even reach peak temperature before going to the red. Also i have replaced the t-stat thinking that the old one may have not been functioning properly and still i have the same problems.

What ARE those codes? That is a big clue.

I understand these engines have 2 temp sensors. The car’s engine computer reads both and one must be a bit lower than the other or an error occurs and the gauge drops to zero. I believe the cooling fans then go to their “high” setting in case the engine is overheating.

Check the wiring to the temp sensor you replaced to make sure it isn’t corroded or damaged. Find and check the second sensor’s wiring. You may also want to change the second sensor.

just 1 code p0128.

Plucked off the internet…

P0128 Causes

  • Stuck open thermostat - Okay, you fixed that unless the one you bought was bad or you pit it in backwards
  • Faulty coolant temperature sensor - You replaced ONE of them
  • Faulty wiring for coolant temperature circuit As I said, check this!
  • Radiator fan constantly running - As I suggested, when the 2 sensors don’t match the fan is running on high speed

Check all these things and fix what you find you will likely find the cause!

Ok. Sounds good, I can honestly say this is the best help I have had since this problem has started. Thank you. I will post if and when i fix the problem.

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