P0492AIR System Insufficient Flow Bank 2
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- After a cold start the secondary air pump blows fresh air behind the exhaust valves so that unburnt fuel burns off and the catalyst heats up faster; CARB requires the air flow to be monitored per bank. P0492 means too little air reaches bank 2 (the side without cylinder 1). VW and Audi calculate the injected air mass per bank from the front oxygen sensor's reaction during the cold-start phase; an Audi bulletin names values of 0.4–0.7 on both banks as too little together, often from coked air passages in the cylinder head. On VW/Audi V engines each bank has its own combination valve with a shared pump. Ford assigns the code to the bank 2 secondary air monitor; GM uses P0411 instead.
- What you may notice
- Check engine light on
- No change in driving
- Secondary air readiness not set (emission test)
- Possibly no pump noise after a cold start
- Likely causes
- LikelySecondary air passages in the cylinder head coked
- LikelyCombination valve stuck or stiff
- PossibleVacuum supply or changeover valve leaking, valve closes too early
- PossibleSecondary air pump weak or water in the pump
- RareHose between pump and valve leaking or off
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €100 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.