My check engine light came on an showed 0420, but half hour later turned off! Should I use Cataclean or CRC catalytic converter cleaner? Or should I change O2 sensors? I don't think I can afford to change the catalytic converter yet.
The computer has sensed a (pending) failure, it recycled & didn't record a second (pending) failure that is why the light went off. Use the cleaner as it will buy you some time, replace when the light stays on all the time. Walker is oem aftermarket for the cat.
I had a 6 banger 1998 Ford Taurus that threw a code for one of the 4 sensors. I replaced it. It then threw a code for the other sensor on the same side so I replaced it. Then it threw a code for the other side so I just replaced both on that side. I also had a 1996 Ford Taurus and about 6 months later it threw the first code so I just replaced them all and never had to deal with it again.
Now if I get a code I just replace them all and don't mess around. Like I said, I've never had to replace a cat.
After 400 miles and a few days of driving with Cataclean, CEL P0420 went away. It's 24 Fahrenheit here today. I don't think Cataclean didn't anything. Haven't changed the catalytic converter or O2 sensors.
For my accord, cataclean did the same, but it didn’t last long. After 2 weeks the CEL was back. No 2 cars are alike, so maybe you’ll be more fortunate than I was.
The Cataclean did some cleaning on the O2 sensor contacts, also a little bit of cleaning in the cat. If the light comes back on you can try the cleaner again, it may work or not but @ some point you will have to replace the O2 sensors.