P2440
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.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Switching valve stuck open by carbon or corrosionCommon
- Carbon or debris buildup preventing free movementLess likely
- Component wear with age - mechanical playLess likely
Parts involved
- Secondary Air Switching Valve
- Secondary Air Pump
P2440 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.