P0410: OBD-II code P0410 flags a general fault in the secondary air injection system — the PCM commanded air injection but doesn't see the expected O2 response at cold start.

Symptoms

• Check engine light is on; the engine drives normally but cold-start emissions clean-up is impaired.
• You may not hear the air pump run at cold start, or it may run continuously when it shouldn't.
• The vehicle will fail an OBD-II emissions test until the secondary air monitor completes clean.

Common causes

• A failed secondary air injection pump — commonly seized or with worn brushes.
• A blocked or corroded air injection hose, one-way check valve, or manifold passage restricting flow.
• A stuck-closed control solenoid or a failed vacuum switching valve preventing pump activation.

What to do?

Command the secondary air pump on with a scan tool at cold start and listen for it running. Test its current draw with an amp clamp. Inspect hoses and one-way check valves for rust and blockage. Replace the pump or valves as diagnostics indicate.