Is this normal, or a "soft" code? When I turn the key to start the car, it flickers right when the car tuns over and then goes out. Car is a '95 Legacy with 132K.

 

As of late, it has come on for real about once a month, usually in 4th gear in overdrive, light throttle on a slight incline; I reset it by disconnecting the battery for 30 minutes.

 

I've stopped bothering getting it reset at Autozone or the garage because I know what it will be: PO420. Am I delaying the inevitable O2 Sensor replacement?

 

The car has always passed inspection and runs and drives just fine. Will they be able to tell anything at the garage when I get my oil changed on Thursday? Anything like stored codes or events, or have I erased all that by disconnecting the battery?

 

I guess I just can't really justify putting a lot of money into diagnostics and sensors and/or a new converter for a 13-year old car as long as the light stays off for a while when it's reset.

 

Any input or comments welcome.

 

Thanks,

Brian

Hi. It might just need a new front o2 sensor. That can cause a situation where the rear o2 sensor triggers P0420. (I assume your '95 is ODBII). If it is just P0420 (and you should still pass inspeciton, since '95 is not required to pass ODBII inspection reuirements).

Good point. It is OBDII. I can deal with front 02 if it comes to that. Perhaps my gas mileage would perk up a bit from the 21-22 MPG I'm seeing around town right now? I know it's winter blend gas and it has been cold. But I can still get 26-28 on the highway, so I'm not terribly concerned.

 

Brian

Good point. It is OBDII. I can deal with front 02 if it comes to that. Perhaps my gas mileage would perk up a bit from the 21-22 MPG I'm seeing around town right now? I know it's winter blend gas and it has been cold. But I can still get 26-28 on the highway, so I'm not terribly concerned.

 

Brian

 

Yes it will. Since you are OBDII use an OE O2 sensor for the front snesor.

 

nipper

Yes typical causes of soob P0420 include front o2 sensor issues, rear o2 sensor issues, exhaust leaks, aftermarket exhaust, and others.