Cherry hot new catalytic converter on my 1991 4.9 L Cadillac Deville I just bought a new code read and O2 sensor seem to be running lean all the time.
I think my new catalytic converter is going bad it looks cherry hot under the car but the car seem ok but some what bad gas mileage what should I check?

My mpg is 5.1 city if my driving habits are decent should it be closer to 11mpg?

Any help would be grate just bought a actor 9145 tester the tps seems high not sure its say .78 Volts should it be lower or is this cause the cpu is trying to adjust it?[&o]

 

your cat. is clogged replaced it

 

It was a bad O2

 

My friend had the same problem, it his GM catalytic converters was clogged... Didn't know though what he did to unlogged it.. I could him later...

 

When they glow cherry red it is not long until the unclog themselves, usually by making one hell of a bang. Deal with it before this happens. Until you do they suck away power and gas. I know you said O2 sensor but deal with that cat too.