P2439 Secondary air system: signal drops out at times (bank 2)
P2439 means: Secondary air system: signal drops out at times (bank 2). The secondary air system blows air into the exhaust on a cold start so the catalytic converter warms up faster. OK to drive, but have it checked soon. The most common repair costs about €45–90 in Estonia, depending on make and model.
What it means
The secondary air system blows air into the exhaust on a cold start so the catalytic converter warms up faster. The computer found too little air or a fault in the pump or valve control. The signal drops out now and then. The most common cause is a loose connector or a chafed wire. Bank 2 is the side of a V engine without cylinder 1.
What you may notice
- Engine light on
- Unusual pump noise on a cold start
- Usually no change in driving
What could be wrong
- 1Connector loose, damp or corroded · Wiring or connector repair €45–90
- 2Wire broken or chafed · Wiring or connector repair €45–90
- 3Faulty air pump or valve · Secondary air pump or valve replacement €200–400
- 4Engine computer fault (rare) · Control unit check and software €150–300
Repair difficulty: Moderate
What you can check yourself
First look at the connector and wiring: anything loose, melted or green with corrosion? On a cold start, listen for the pump droning in the engine bay for a few seconds. You can check the simple things yourself, but the repair is best done in a workshop.
How we fix it
- We read the fault data on the diagnostic tool and check whether the fault is constant
- We measure the circuit's supply, ground and signal
- We repair the wire or replace the connector
- If the wiring is fine, we replace the air pump or valve
Standard SAE description: Secondary Air Injection System Air Flow/Pressure Sensor Circuit Intermittent/Erratic Bank 2