I had a garage replace my timing belt, and when I got the car back, it had the check engine light on with P0420. The mechanic cleared the code, and I filled up the tank with premium Shell V-Power with a bottle of Techron thrown in, and the check Engine light stayed off for the whole tank of gas. I refilled it with regular gas, and the light came back on. Any ideas?
Any help here, please.
that code refers to the catalytic converter efficiency. it compares the waveform of both oxygen sensors(one before the cat and one after) if the cat is working properly the waveforms will be much different but when they become similar the computer tells you either your cat is no longer working very well, or an oxygen sensor is FUBAR, you need the proper tools to test and diagnose this or you can go out and buy a cat and 2 oxygen sensors,(not recommended)
Thanks. Do you know why the techron made the light stay off?
did you ever find out what the issue turned out to be?
I have a CRV that just had the timing belt changed and the same code come up when my check engine light came on.
Any info woudl be great.