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Ask RussMasterTech Your Own Question
RussMasterTech, ASE Certified Technician
Category: Chevy
Satisfied Customers: 791
Experience:  19 years of GM Dealership experience. ASE Master with L1 and GM Master Certified in Electrical
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2002 chevy impala, heat temperature sensor

Customer Question

If this is a common problem with this car, why isn''t GM doing anything? I have had this car repaired on a monthly basis since I bought it. Intake Manifold, Windshield Wipers, Radiator Flush (just last week), Water Pump (just last week) and now the heat temperature control wire is faulty and I need to take it to either the dealer or a "specialist" to have them diagnosis it for $100, then tell me how much it will be to fix it. The temperature guage keeps going over the middle mark, sometimes to the red zone, and the car is heating up. Any advice?
Submitted: 8 years ago via
Category: Chevy
Expert:  RussMasterTech replied 8 years ago.

Hello sissypot,

I'm not sure the sensor or the wiring are bad if the engine is running hot. All of the work that you've had done have all been seperate issues, but they may have aggravated an underlying issue of a failing head gasket. If the temp is going high like that since the water pump and the flush were performed, there is a good chance the tech that replaced the pump and did the flush did not bleed the air out of the system correctly. There is a specific fill procedure for this engine, and if it is not followed, overheating and engine damage can result.

With the engine off, and the radiator cap off, open the bleeder screws, one at the bypass pipe above the water pump and one at the upper hose outlet on the driver's side front corner of the engine where the upper hose connects. Fill the cooling system with a 50/50 mix of Dexcool and water until just coolant and water come out of the bleeders, NO AIR. Close the bleeders and top off the coolant.

If you got alot of air, or if it continues to overheat, you may have a head gasket failing that is allowing combustion gasses into the coolant which prevents proper coolant flow.

If you take it to a shop, have them perform a combustion gas analysis on the cooling system. This will be a clear chambered tool with a squeeze ball on one end. The tech will fill the cylinder partially with a blue "Test fluid" that will turn yellow if there is combustion gas present in the coolant. This will verify my suspicions.

Depending on how long you drove the car with low coolant prior to any of the previous repairs may have started this chain reaction, but I don't want to speculate. I just want you to understand what could be going on.

If you have additional questions related to this concern, or other information you wish to share with me to help me understand what's going on, please feel free to reply before clicking the "Accept" button.

If this is the information you were looking for, please make sure to click the "Accept" button so I may receive the credit for helping you today. Positive feedback is always appreciated.

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Customer: replied 8 years ago.
Reply to RussMasterTech's Post: Thanks. I did do that (check for the air), when the Radiator flush was done, that was the problem. So it went to a mechanic who took the air out. That was before the water pump went out. Now he's saying that its a wiring issue with the electronic heat sensor (or something), and as a result, the fan (high) isn't kicking on when the engine gets hot and then the temperature gauge goes over
Expert:  RussMasterTech replied 8 years ago.


I don't think he's going down the right path. The sensor that he is reffering to is the ECT or Engine Coolant Temp sensor. This sensor responsible for telling the computer how hot the engine coolant is AND to let the Instrument cluster know how how hot the engine coolant is. If the gauge is working, then the computer is getting the signal. If the fan is not coming on, there could be a problem with the fan or the relay.

Does the service engine soon lamp some on? If so, did he tell you which code has set? This might help me understand where he's coming from.