DTC P0491: Secondary Air Injection (Air) System Insufficient Flow (Bank 1)

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P0491 - SECONDARY AIR INJECTION (AIR) SYSTEM INSUFFICIENT FLOW (BANK 1)

Description:	The AIR system detected that there was insufficient mass air flow change during pump switching (ON/OFF).
Possible Causes:	Secondary AIR pump with no or low air flow. Secondary AIR bypass solenoid leaking/blocked or stuck open/closed. Secondary AIR diverter valve leaking/blocked or stuck open/closed. Secondary AIR air hose restricted. Secondary AIR vacuum hoes restricted or leaking.
Diagnostic Aids:	Measured air flow is less than expected. Visually inspect the secondary AIR inlet hose.
Application	Key On Engine Off	Key On Engine Running	Continuous Memory
All	-	GO to Pinpoint Test HM .	GO to Pinpoint Test HM .