P0420 Chevrolet -Aveo 2005

Question

with rough idle and just recently P2279 has appeared replaced the throttle body but no change and the timing has been checked and is perfect , smoked the intake system and could not find any leaks

Answer 1

P0420 Catalytic below threshold Bank 1

P2279 Intake air system leak

There alot of places for a vacuum leak. such as the purge valve being stuck open or the EGR system. You can block of the purge valve from the intake and retest, you can also block the flow of the EGR using a slice of aluminum can.and retest