Mechanics

WHAT COULD CAUSE THE ENGINE AND OIL RADIATOR FANS TO RUN 100% OF THE TIME

2003 Saturn Station Wagon • 65,000 miles

Check Engine Light is on. Advanced Auto Parts checked codes. Shows thermostat stuck open. Engine and oil radiator fans run 100% when engine is running. Fans don't run with ignition in "on" position but engine not running. Could thermostat be the problem? Also, how hard is it to replace by somewhat experienced do-it-yourselfer? I have new thermostat, but don't want to waste antifreeze.

Thanks

Ron
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Ronsanders@columbus.rr.com
November 21, 2011.




What is the EXACT troukle code youar getting?
What is your vehicle model code?

KHLow2008
Nov 21, 2011.
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.

Just to add to thos one sounds like you a code P0128 is that correct?Also if you have a wagon that year it can be only one model the LW. If you have the 2.2L engine not to bad replacing the thermostat but if you have the 3.0L then to replace the thermostat you have to pull the intake plentuim without tearing any of the intake boots. Also you have to be careful when pulling the thermostat inlet tube out of the thermostat housing so you dont break the tab the bolt goes in that holds the tube in place.I would say that one is a more advanced job. As far as the fans always staying on the fan relay modules go bad but when that happens they usually stay on with the key off also. Another thing that comes to mind is a bad miss fire will keep the fans on while engine is running. If you run the idle up to about 2,500 rpms in park for a min or two will the fan shut off?

Saturntech9
Nov 21, 2011.
I do have the LW200 2.2L engine. I have replaced the thermostat and while at it, flushed the radiator system. I had the incorrect milage initially. Not 65,000 but 103,000. The radiator coolant had never been flushed so since I was replacing the thermostat (quite easy I might add). After a fresh fill of 50/50 antifreeze, and the engine running about 15 minutes, no leaks were detected and the fans did return to the normal (not running constantly) state. The temperature gauge is up to where it used to be before the "check engine" light came on. The check engine light is still on. Do I have to do something else to clear the "check engine" light?

Thanks!

Ron

Have you tried clearing the code with a scan tool?

Saturntech9
Nov 22, 2011.
Hi Saturntech9! I don't have a scan tool and the cost to get one at this time is prohibitive. I've checked with several local retailers around the area and was told they don't clear codes anymore as there has been a lot of misuse of this process. I'm still checking around to see if somebody will do it for free. I'm not paying $50.00 - $100.00 to have somebody clear the codes for me.

You can get a basic reader and clearer for about 40.00 if you dont have a smog in the near future it will clear on it own over time.

Saturntech9
Nov 22, 2011.
Hi Everyone! Thanks for all the help above. The system did clear itself today after running it on the highway for about 30 minutes. Maybe just running it around town didn't clear things up, but the freeway driving did. The check engine light is no longer lit, no leaks from the thermostat area, radiator is now full, and the car is good to go another 100,000 miles.

Again, thanks to all who responded.

Have a wonderful Thanksgiving!

Your welcome thats what were here for.
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Saturntech9
Nov 23, 2011.

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