Forgot to comment on other suggestions. Yes, there was a bit of an exhaust leak that I noted earlier. Replaced the donut and the leak went away. This was after having the cat replaced for the first time. Didn't change the CEL. Mileage has always been in the mid-20's to low 30's. So we haven't seen a...

I think that the problem is solved. I purchased defoulers and drilled one out to 1/2". When I took out the rear O2 sensor, I found that its diameter was too large to fit into the 1/2" hole in the defouler. I went ahead and bought a Denso direct fit sensor and installed that with the defoul...

Engine doesn't burn oil and is not blowing antifreeze out the exhaust system.
I found info on spark plug non-foulers. Will pick up a pair and install. I'll let you know what happens.

Thanks for the replies. They replaced the front sensor. I will have to check on what brand they used. The P0130 and the P0133 codes have gone away. We are only getting the P0420.

I've not heard of a $10 defouler. Can you explain?

Thanks in advance.

My daughter has an '03 Vibe GT. It now has 155K on it and has generally been very reliable. We live where an emission check is mandatory every 2 years in order to renew your registration. So... a little more than a month ago, her check engine light came on. We took the car to an independent repair s...