P0491 Acura Secondary Air Injection System Insufficient Flow Bank 1
Possible causes
– Secondary air pump with no or low air flow
– Secondary air bypass solenoid leaking /blocked or stuck open /closed
– Secondary AIR air hose restricted
– Secondary air vacuum hoses restricted or leaking
– Secondary air bypass solenoid leaking /blocked or stuck open /closed
– Secondary AIR air hose restricted
– Secondary air vacuum hoses restricted or leaking
Symptoms
– Engine Light ON (or Service Engine Soon Warning Light)
P0491 Acura Description
The secondary air system detected that there was insufficient mass flow change during pump switching (on/off)
Acura Vehicle:
Acura ILX, Acura MDX, Acura RDX, Acura RLX, Acura TL, Acura TSX, Acura ZDX, Acura CSX, Acura EL, Acura Integra, Acura RSX, Acura Legend, Acura Vigor, Acura CL, Acura SLX, Acura NSX, Acura RL, Acura ZDX