Ive got a 2001 GMC Sonoma that runs great, but it wont pass emissions. Ive spent more money than the truck is worth on repairs, and its gotten me nowhere.

A" P0410 secondary air system malfunction" is the code that keeps coming up and preventing the truck passing from the obd test, and i also qualified for an emissions waiver to have the county emissions station test it with the exhaust sensor but it failed due to CO levels being to high. I thought the waiver was for situations like mine but apparently not.

Ive replaced every component of the secondary air system, the air pump (twice in the past 30 days), air pump relay, air pump solenoid, vacuum shut-off valve, both check valves, and new hoses. My mechanic is stumped, and the dealership and 1 other shop did diagnostics and reccomended replacing the pump which ive already done twice.

I don't know if the high CO levels are related to the secondary air system malfunction. I need to figure out how to fix either the p0410, or figure out whats causing the high CO levels or find a shop that can help me, because so far 3 different places have done nothing but take my money.

Im now driving with expired tags even though i already paid for the registration. Ive used up all the temp permits they will give me but i have no choice but to keep driving it as im a contractor and can't work without my truck. I don't know what else to do.

Any ideas, suggestions, shop referrals, or advice would be greatly appreciated.