The fans might be running all the time if the temperature sensor is bad and stuck in a position that makes it think it is always hot enough to run the fans. This would trigger the rest of the sytem as just the relay being bad would not do this. If your car has a temperautre gauge, make sure you change the right sensor as there are usually 2 sensors. One for the gauge and one for the cooling system.
The thermostat being stuck open would make the engine run cold and I find that an odd code to come up. If the thermostat has a sensor on it to send a trouble code it may be part of the circuit, which I have never heard of and find the trouble code odd and maybe even not very reliable a trouble code, I would think that it being stuck closed, not open would be an issue. A thermostat stuck open would cause overheating as soon as operating temperature was reached and not before, so the fans would not kick on until it reached that temperature. That is what makes me think the sensor is bad. It is not hard to replace and is usually near the thermostat and either on the head or on the thermostat housing itself. It and the thermostat are not hard to replace or get to, unless the system uses an oil temperature sensor for the fans then the sensor could be on the back of the engine in most cases and you have to get under the car. Still not hard though and oil will not spill everywhere. Replacing the thermostat and sensor will let some anti-freeze spill out and it will have to be topped off. Don't get confused over the oil temperature sensor turning on the fans as it will still use 2 sensors as I stated before, it is just in a different location.
Monday, November 21st, 2011 AT 5:47 PM