P2440 on Volkswagen: How to Diagnose & Fix
Secondary Air Injection System Switching Valve Stuck Open (Bank 1)
2 Volkswagen models · 2 documented issues · $300-$1,200 repair
P2440 on Volkswagen by model: symptoms, diagnosis and fix
The petrol V8 and W12 engines have a secondary air injection (SAI) pump used during cold start to reduce emissions. Moisture (naturally present in exhaust) backflows through worn one-way check valves into the pump, corroding/freezing it and causing failure. This triggers a check-engine light with SAI codes. On the Phaeton the pump sits above the front of the left wheel-well liner. A frequent re-failure cause is not fitting the drain tube to the pump housing during replacement.
Common Symptoms
- Check engine light
- Failed emissions test
- Audible pump whine on cold start or no pump sound at all
- Rough cold-start running
How to Fix
Read codes to confirm SAI fault. Test/replace the one-way check valves and the SAI combination/switching valve, then replace the air pump if seized. When replacing the pump, fit the housing drain tube to prevent repeat moisture-induced failures.
What you need to diagnose it
The repair instructions explicitly call for reading stored codes. Use a scanner that can read the named code families before choosing a repair.The recommended scanner supports these code families; confirm your exact year, model and module coverage before buying.
ANCEL AD310 Classic OBD-II Scanner
Read & clear engine (P) codes
$20–$40View
As an Amazon Associate, we earn from qualifying purchases. Prices are approximate and may vary.
Reading and clearing the code is DIY work. Module replacement or reprogramming is not — most modules are VIN-programmed, so a new one does nothing until a shop codes it to your car. Check for an open recall or service bulletin before buying anything.
Sources for this issue (2)
The 2.5L five-cylinder Jetta (Mk5 2005-2010 and Mk6 2011-2014, engine codes BGP/BGQ/CBTA/CBUA) very commonly fails its secondary air injection system, which pumps air into the exhaust on cold start to light off the catalyst faster. The root cause is almost never the pump itself: the one-way combination valve (combi valve) between the pump and the exhaust fails and lets hot, moist exhaust gas back into the pump. That moisture corrodes the pump internals and, in winter, freezes - which is why many failures announce themselves on the first hard freeze, often blowing the pump fuse or burning out the J299 relay. The signature is a loud jet-engine or shop-vac roar for 60-90 seconds after a cold start, followed by a check engine light. The system only runs on cold start, so the car otherwise drives normally, but it is an emissions-test failure.
Common Symptoms
- Loud jet-engine or vacuum-cleaner noise for about a minute after cold start
- Check engine light with secondary air injection codes
- Emissions test failure with readiness monitors incomplete
- Blown secondary air pump fuse, particularly in freezing weather
- Rough or elevated idle for the first minute after a cold start
How to Fix
Diagnose properly before parts-swapping: check the J299 secondary air pump relay and its fuse, inspect the rubber hoses between pump and combi valve for cracks, and test the combi valve for leak-back. The critical rule owners repeat is that the combi valve MUST be replaced whenever the pump is replaced - fitting a new (or used) pump behind an old combi valve simply destroys the new pump. Expect pump plus combi valve plus hoses. No recall exists; this is a customer-pay repair once out of the federal emissions warranty (8 years/80,000 miles on emissions-related components may cover some cars).
Sources for this issue (3)
P2440 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P2440 mean on a Volkswagen?
P2440 stands for "Secondary Air Injection System Switching Valve Stuck Open (Bank 1)." P2440 indicates the secondary air injection (SAI) system's switching/diverter valve on engine bank 1 is stuck open. The secondary air system briefly pumps fresh air into the exhaust at cold start so the catalytic converter heats up and lights off faster, cutting cold-start emissions. The computer commands this valve closed once warm-up is done; if it senses the valve hasn't closed (air is still flowing when it shouldn't be), it sets this code. A stuck-open valve can let exhaust pressure or moisture back into the air pump and skews the oxygen sensor readings during warm-up. On Volkswagen it is documented across 2 models: Phaeton, Jetta.
What are the most common causes of P2440?
The most common causes of P2440 are: Air switching/diverter valve stuck open or seized, Carbon, rust, or debris fouling the valve, Faulty valve vacuum control solenoid or leaking vacuum line, Corroded or moisture-damaged secondary air pump, Wiring or connector faults at the valve solenoid, Clogged or failed combination/check valve, Vacuum leak preventing the valve from closing. The specific cause varies by vehicle.
How much does it cost to fix P2440 on a Volkswagen?
Published repair estimates on Volkswagen range from $300 to $1,200 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P2440 on a different make?
View P2440 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.