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Toyotapro, ASE master tech
Category: Toyota
Satisfied Customers: 9974
Experience:  ASE Certified, 10+ years Lexus and Toyota Certified
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Toyota Camry CE: Question about a 2000 Toyota Camry, 2.2L 4

Customer Question

Question about a 2000 Toyota Camry, 2.2L 4 cyl. P0128 code and radiator fan issue.
The radiator fans (both) run constanly, even from turning the key on to accessory just be for starting the engine as well as when the engine is running. I have replaced the radiator fan temperature switch as well as the coolant temp sensor with Auto Zone Duralast aftermarket replacements, but both fans still run continuously. The only way to stop the fans is to remove both fan relays from the fuse block, and of course the fans stop. Could it be possible both fan relays have failed in the stuck closed position? I am uncertain as to how to ohm out the relays to verify that possibility.
The P0128 (coolant temperature below thermostat temperature) will reset, but will eventually throw the code again later on. With both fans running the OBDII analyzer incates a coolant temp of ~130°F while the car sits still at idle on a 45°F day, and drops even cooler while moving down the road of course. I figured the code is a direct result of the radiator fan running issue, but not certain of that either.
I am at a loss, so any professional help on this would be greatly appreciated.
Submitted: 5 years ago.
Category: Toyota
Expert:  Toyotapro replied 5 years ago.
Hello and thank you for using just answer! Do the fans run if you unplug the a/c high pressure switch?
Customer: replied 5 years ago.
I have not tried that. I am not aware of that switch or where it is located. Can you give me guidance as to where it is located?
Expert:  Toyotapro replied 5 years ago.
Follow the a/c pressure lines, toward th front there is a 5 wire switch plugged into a sensor on the metal lines.
Customer: replied 5 years ago.
Okay, I had to leave for a while. This car is my neighbors car, so I will have to check it tomorrow to see if unplugging this switch causes the fans to shut off. If it does, I take it that the switch is bad and needs to be replaced? If it doesn't what would be the next thing in the line of items to check that would possibly cause the fans to stay on?
Expert:  Toyotapro replied 5 years ago.
The second item I'm wanting looked at here is the other coolant sensor. Most of these have 2, one near the coolant housing on the engine block and the other on the radiator.
Customer: replied 5 years ago.

I looked all over the radiator and could not find a sensor mounted directly on the radiator. There are two sensors on the thermostat housing/outlet from the engine return to the radiator. I have replaced both of these sensors. One is the temperature sensor, the other is what is listed as the fan temperature switch. Replacing both of these units did not solve the issue.

I will be working on the car this afternoon to replace the 0-rings and insulators3 on the injectors and rail. I will pull the high pressure refrigerant switch connector to see if that solves the problem and will get back with you to let you know if it shut the fans off.

Expert:  Toyotapro replied 5 years ago.
Ok thanks
Customer: replied 5 years ago.

Hello. I found the problem. I located what I think is the fan temp switch. It is in the lower radiator below the passenger side fan. It is missing the connector plug and wire. I think the problem is solved.

Thank you for your assistance. I will leave positive feedback for you.


Expert:  Toyotapro replied 5 years ago.
That isn't a fan temp sensor sir, that's the second coolant temperature sensor that I had previously mentioned. This second sensor is what sends the computer the coolant reading for fuel mixture reasons.