DoraDexplora

I have a 96 Explorer with 110,000 miles on a 6 cylinder with a check engine light on for code P0420, cat going bad. A few months ago, the light was on for P0154, o2 sensor not responding, but that must have cleared itself up since the only code now is P0420. Pep Boys and 95 bucks will tell you to replace the cat, does anyone know if they are right?

I may be nuts but found through research that a stuck thremostat was the only thing that can kill a cat which I had for a year or two until it stuck closed and needed to be replaced.

Any help would be appreciated.

Dora.

 

LunaticSVT

Well, p0420 is Catalyst System Efficiency Below Threshold(Bank 1). This could mean that the CAT is having issues or even one of the O2 Sensors are defective. With you stating that you had a P0154 which is the O2 Sensor Circuit No Activity Detected (Bank 2 Sensor 1) While this is on the opposite side from the issue in question I would look at your O2s first.

Cheap quick and dirty test. Have the codes cleared. Take your precat and postcat o2 sensors and swap sides. not front to rear, but left to right. Run the vehicle for 30 miles and then go and check the codes again. If the codes change from p0420 to p0430 you know it is the o2 sensor. If it stays as the p0420 then it is the cat.

I know most do not want to do this, but it does work.

DoraDexplora

Great idea, I will give it a try.

Thanks.