Secondary Air Injection System Switching Valve Stuck Open (Bank 1)
The switching/check valve in the secondary air injection plumbing on bank 1 is stuck in the open position. With the valve permanently open, exhaust gas can back-feed into the air pump and corrode it, while the downstream O2 sensor sees ambient air constantly.
Affected components
- Secondary air switching valve
- Secondary air pump
Common causes
- High likelihood: Switching valve stuck open by carbon or corrosion
- Low likelihood: Carbon or debris buildup preventing free movement
- Low likelihood: Component wear with age - mechanical play
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
- A drive cycle may be required after repair
Related codes
Sources
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.