05 Envoy

[juliek]

1st thing in the morning when I start my car it smells like
rotten eggs. That's the only time to.

 

[Molson02536]

1st thing in the morning when I start my car it smells like
rotten eggs. That's the only time to.

The rotten egg smell (sulphur) is not from a bad cat, it is a reaction going on in the cat from too much fuel. 99 times out of 100 it is not the cat at fault but either a bad map sensor or a bad O2 sensor. Both cause too much fuel to be in the mixture and the result from that is the smell. I'm surprised you aren't getting a check engine light but the first thing I'd do is get DTC codes read.

Start with a tune up, Spark plugs, air filter, ECT and clean you Throttle body and add fuel injector cleaner in your gas tank. Good luck and remember you have a Emission Control Systems Warranty 8 yr/130,000 km o Specified Major Emission Components. "Catalytic Converters and Powertrain Control Modules"