Cause
Blocked secondary air pipework
Carbon and corrosion narrowing the passages carrying pumped air into the exhaust. The pump and valve can be perfect and the flow still fails the test, which is why the flow sensor reports a fault that no amount of pump replacement resolves.
Typically a moderate job.
Codes this can cause (7)
Codes where this is a likely explanation first, rather than merely a possible one.
- P2431 Secondary Air Injection System Air Flow Pressure Sensor Circuit Range/Performance Bank 1 Likely for this code Moderate
- P2436 Secondary Air Injection System Air Flow Pressure Sensor Circuit Range/Performance Bank 2 Likely for this code Moderate
- P2435 Secondary Air Injection System Air Flow Pressure Sensor Circuit Bank 2 Moderate
- P2441 Secondary Air Injection System Switching Valve Stuck Closed Bank 1 Moderate
- P2443 Secondary Air Injection System Switching Valve Stuck Closed Bank 2 Moderate
- P2445 Secondary Air Injection System Pump Stuck Off Bank 1 Moderate
- P2447 Secondary Air Injection System Pump Stuck Off Bank 2 Moderate
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