04 Sierra 1500 4.8L Check Engine Light is on check with code checker at parts store and it read "catalytic system reading above threshold (bank 2). Everyday for a few days I went back to the store and cleared it. It seems that it only comes on when idling. Any help appreciated from an experienced technican!
Catalytic system above threshold (bank 2)
- Thread starter alno1995
- Start date
Molson02536
New member
Chances are that the O2 sensor will need to be replaced, if it's your Catalytic Converter that has gone bad. You would hear rattles or have some type of restrictions and it should be covered by the emission warranty up to 8 years or 130,000 KM or 90,000 miles.
Just make sure you pick up and OEM O2 sensor, after market O2 sensors i find go bad twice as fast as the OEMs. Good luck and it's the O2 sensor after the Catalytic converter that needs to be replaced, but recheck all the wire leads first and look for any damages.
Catalytic Converter
Correct Answer! Took it to the dealer code P0430 was for bad Cat. Since there is a Federal warranty for 8 Years and 80,000 miles the replacement cost even the diagnostic, gaskets was FREE!. Also had Evap code which a post lead me to believe it was a bad evaporative vent valve which is mounted to the fuel tank. Easy, inexpensive fix for $17 from rockauto.com or a GM dealer. You have to run 5/8" tubing about 2' because you can't replace the plastic OEM tubing. But that will clear up any GAS CAP CODE for the most part. If it is not that it could be the Evap Purge Valve which is easy to get to on top of the engine under the Vortec cover just to the left in the front.
Correct Answer! Took it to the dealer code P0430 was for bad Cat. Since there is a Federal warranty for 8 Years and 80,000 miles the replacement cost even the diagnostic, gaskets was FREE!. Also had Evap code which a post lead me to believe it was a bad evaporative vent valve which is mounted to the fuel tank. Easy, inexpensive fix for $17 from rockauto.com or a GM dealer. You have to run 5/8" tubing about 2' because you can't replace the plastic OEM tubing. But that will clear up any GAS CAP CODE for the most part. If it is not that it could be the Evap Purge Valve which is easy to get to on top of the engine under the Vortec cover just to the left in the front.