I have recently purchased a 2003 Monte Carlo SS. I have always driven a chevy, never one with electric fans. At what temp should the fan or fans come on? When I turn on the a/c the fan on drivers side kicks on and off but the other fan hasn't come on. And the check engine light comes on with a code of P0420 and the censor has been replaced.

 

goggle that code it came up 02 sensor/catalytic conveter.you replace the o2 sensor and if it was your cat the check engine light would stat on.??check the sensor again

 

thanks! will do that. it has an aftermarket converter on it.....

 

well depending on which type of cat u have on it can cause the dtc