One or both secondary air injection check valves may become restricted causing poor air flow resulting in illumination of the Check Engine Light. It is often recommend to replace both check valves even if a fault code is set for only one bank of cylinders. Replacing only one valve may result in a return trip to the repair shop.Google+
Car Problem Reports
GMC Sierra 1500 Check Engine Light Due to Restricted Secondary Air Injection Check Valves
GMC Sierra 1500 Problem
Average Mileage: 100,037 mi (80,000 mi - 135,000 mi)
Visitor, 2000 GMC Sierra 1500, 135,000 mi
ck engine light , scan indicates secondary air injection problem
Visitor, 2000 GMC Sierra 1500
check engine light stays on . i have had the computer scanned a few times by different people and the only codes that ever come up are , secondary air injection bypass valve. so today im gonna change both of them .
Visitor, 2001 GMC Sierra 1500, 85,000 mi
The dealer said the problem was a faulty Air Check Valve - Part # 12567733. The cost of the part was not
too bad but the labor they stated was out of hand. Other forums discuss the replacement and step by step
procedures while stating it not difficult or time consuming to replace. Apparently the dealer I visited
has not read this posting.