Hi, and thanks for looking. I know little about engines, hoping for a little help. My check engine light went on recently, and when i used a diagnostic tool, I got the code P0483 Cooling fan malfunction rationality check. In the list of monitors the following 3 items were marked n/a, HTO catalyst, sec. air system, and A/C refrigeration monitor. Then a couple days ago, I left the power on, killing the battery, and bought a replacement, and now the check engine light is flashing! Any advice on any of this?

That code can be set for several reasons. The ECU looks for a change in engine coolant temp after the fan is commanded On. If the temp doesn't change X amount of degrees in Y amount of time, it sets a code.

 

First thing is to make sure the fan actually works. Look under the dash on the drivers side and find the two small green connectors and plug them together. Turn the key On and the ECU will be in test mode. All of the relays and solenoids will cycle in roughly 1 second intervals. The cooling fans will cycle low high off. Make sure both fans work on both speeds.

 

Is the check engine light blinking while the engine is running?

 

 

Those three monitors marked N/A are because your vehicle doesn't have any of that equipment to monitor.

Thanks for the fast answer! I looked under the dash, found the connectors, and they were already hooked together. I unhooked them, and now the check engine light is off. I'm not sure if that means it was hooked up the whole time, or if they hooked it up at the garage a couple days ago and didnt unhook it. Maybe it was originally a problem resulting from a low battery, which would be solved now, and the flashing light was trying to tell me that the engine is still in "test mode"? Thanks so much for the help.

I turned the car on in and out of test mode, and listened for the cycling you described.(check engine light blinks when in test mode) Wasnt sure what to look for, but in test mode there were changes to the sounds from the engine at pretty regular intervals which I didnt hear when it was not in test mode. I dont know how to judge if they sound correct, but they seemed like more than 1 second intervals sometimes, if that helps.

HI,

Yes, w/the Green connectors connected the sensors on/around the engine will cycle on/off, including the fans....that's normal to tell you they're working (or not).

 

On the older Subarus pre-95, the green connectors could be used to diagnose AND clear codes. I'm not sure if that applies to the '95+ models.

 

Td

Edited June 11, 201510 yr by wtdash