P2440 on 2011-2014 Audi A6 3.0T: Secondary Air Valve Stuck Open Causes and Fixes

What's Unique About the 2011-2014 Audi A6

What's unique to this Audi platform is the clear diagnostic guidance provided by the manufacturer. A Technical Service Bulletin (TSB 2040403) states that if you only have the P2440 code, the Bank 1 Combination Valve is the likely culprit. However, if you have both P2440 (Bank 1) and P2442 (Bank 2) codes stored at the same time, the single vacuum solenoid that controls both valves is the probable cause. This factory guidance makes diagnosis much more direct than on many other vehicles.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Check Engine Light (MIL) is on.
• In rare cases, a slight rumble or change in engine performance during slow acceleration or deceleration.
• Vehicle may enter a reduced-power "Limp Mode", though this is uncommon for this specific code.

Most Likely Causes

1. Defective Bank 1 Combination Valve 🔴 High Probability As outlined in Audi TSB #A011519 (also listed as 2040403), a defective combi valve is the primary cause for a single-bank SAI code like P2440. The valve is located at the rear of the cylinder head, exposed to intense exhaust heat and carbon buildup, which causes the internal diaphragm or mechanism to fail and stick open.
   How to confirm: With the engine cool, locate the valve on the passenger-side cylinder head. Disconnect the small vacuum line and attach a hand-held vacuum pump. The valve should hold vacuum (around -20 inHg). If it does not, or if you can blow through the main air port with no vacuum applied, it is stuck open and has failed. Some owners report being able to clean out gunk to temporarily restore function, but replacement is the only reliable fix.
   Typical fix: Replace the Bank 1 Combination Valve and its associated metal gasket. Access is tight, requiring a T30 bit on a small ratchet.
   Est. part cost: $100-$250
2. Defective Vacuum Solenoid (N112 Valve) 🟡 Medium Probability This is the second scenario listed in the Audi TSB. This single solenoid controls vacuum to both combi valves. It is the most likely cause if codes P2440 and P2442 (for Bank 2) appear together. The solenoid itself can fail internally over time.
   How to confirm: If both P2440 and P2442 are present simultaneously, the solenoid is the prime suspect. You can also use a capable scan tool like VCDS to perform an output test on the solenoid to see if it clicks and functions correctly. It is located on top of the engine near the throttle body, making it easy to access.
   Typical fix: Replace the secondary air injection vacuum solenoid (Part No. 06E906517A).
   Est. part cost: $40-$90
3. Cracked or Disconnected Vacuum Hoses ⚪ Low Probability The plastic and rubber vacuum lines in the engine bay become brittle over time with exposure to heat cycles and can crack or break, causing a loss of control over the combi valves. This can happen during other maintenance, like a PCV valve replacement.
   How to confirm: Visually inspect all vacuum lines running from the N112 solenoid to both combi valves. Check for obvious cracks, breaks, or loose connections. A smoke test can also reveal hard-to-see leaks.
   Typical fix: Replace the damaged section of vacuum hose or the entire harness.
   Est. part cost: $10-$50

Rare But Worth Checking

• Secondary Air Pump Failure: This typically causes 'insufficient flow' codes (P0491/P0492). However, a stuck-open combi valve can cause the pump to fail from moisture backflow. If the pump is noisy (sounds like a loud vacuum cleaner on cold start) or a related 50A fuse is blown, the pump may have failed as a secondary issue.
• Wiring Issue to Vacuum Solenoid: Damage to the electrical connector or wiring for the N112 vacuum solenoid could prevent it from operating correctly, though this is less common than the solenoid itself failing. A voltmeter can be used to check for 12V at the connector with the key on.
• Faulty SAI Pressure Sensor (G609): A faulty secondary air pressure sensor could incorrectly report to the ECU that the valve is stuck open, even if it is functioning correctly. In some forum discussions, users have noted that this 3-wire sensor can fail, but this is an edge case and less common than the valve or solenoid.

Diagnosis Steps

1. Scan the ECM for codes. Check if only P2440 is present, or if P2442 is also stored. If both are present, the primary suspect is the vacuum solenoid (N112 valve).
2. If only P2440 is present, begin by visually inspecting the vacuum lines running to the Bank 1 (passenger side) combi valve for any obvious cracks or disconnections.
3. Locate the Bank 1 combi valve at the rear of the passenger-side cylinder head. It is a metallic valve with a large air hose and a small vacuum line attached.
4. Disconnect the small vacuum line from the combi valve's port.
5. Connect a hand-held vacuum pump to the combi valve's vacuum port. Attempt to apply vacuum. The valve should hold the vacuum without leaking down. If it does not hold vacuum, it is internally ruptured and must be replaced.
6. If the valve holds vacuum, try to blow through the large port where the air pump hose connects. Air should not pass through. If it does, the valve is mechanically stuck open and must be replaced.
7. If the valve tests good, the issue may lie with the vacuum supply. Reconnect the hose and use a scan tool (like VCDS) to activate the SAI system during a cold start or via an output test to verify vacuum is being supplied and released by the N112 solenoid.

Parts You'll Likely Need

• Secondary Air Injection Combination Valve (Bank 1) (OEM #06E131101M) — This is the most common failure point for a solo P2440 code, as identified by the manufacturer TSB. It fails from heat and carbon buildup.
  Trusted brands: Audi (OEM), Pierburg
  OEM price range: $200-$275
  Aftermarket price range: $100-$180
• Secondary Air Injection Solenoid Valve (OEM #06E906517A) — This is the primary cause if both P2440 and P2442 are present. It controls the vacuum signal to both combination valves. This part is also known as the N80 valve in EVAP systems on other VW/Audi models.
  Trusted brands: Audi (OEM), Bosch, Pierburg
  OEM price range: $60-$90
  Aftermarket price range: $25-$70
• Combination Valve Gasket (OEM #06E131120C) — This gasket is a required one-time-use part when replacing the combination valve to prevent exhaust leaks. The TSB also lists this as a required part for the repair.
  Trusted brands: Audi (OEM), Victor Reinz
  OEM price range: $10-$20
  Aftermarket price range: $5-$15

Related Codes That Often Appear With This One

• P2442 — P2442 is the identical 'Stuck Open' fault for Bank 2 (driver's side). According to Audi's TSB, when P2440 and P2442 are stored together, it strongly indicates a failure of the single vacuum solenoid that controls both valves.

Technical Service Bulletins (TSBs) & Recalls

• A011519 2040403- / 01 16 73 2040403/3: MIL on (DTC P2440(00) and/or P2442(00)). Details the two primary causes (defective combi valve or defective vacuum solenoid) and how to diagnose them based on whether one or both codes are present.

Platform-Specific Known Issues

• Audi released Technical Service Bulletin #A011519 2040403- (also listed as 01 16 73 2040403/3) for the 2012-2014 A6 3.0T, which directly addresses DTC P2440. It states the cause is either a defective combi valve or a defective vacuum solenoid and provides diagnostic criteria to distinguish between the two scenarios.
• Access to the Bank 1 combi valve is tight, located at the rear of the passenger side cylinder head. DIY replacement is possible but requires patience and tools like a small T30 bit ratchet to access the lower bolts.

Mechanic-Grade Diagnostic Values

• SAI Pressure Sensor (G609) Signal Voltage — expected: Approx. 2.9 VDC at rest (pump off).. Failure: A user reported that after replacing the valve, the code returned. They measured the sensor voltage and found it was around 3.3 VDC when hot and 3.5 VDC when cold, suggesting a potential issue with the sensor or the air pump's output pressure affecting the reading.
• Combi Valve Vacuum Test — expected: Should hold vacuum when tested with a hand pump (e.g., -20 inHg).. Failure: If the valve does not hold vacuum, the internal diaphragm is ruptured. If air can be blown through the main port with no vacuum applied, it is stuck open.

Scan Tool Commands That Help

• VCDS (VAG-COM): Engine -> Basic Settings -> Group 077 — This function initiates the SAI system's diagnostic test sequence. The ECU runs the pump and monitors the system, reporting 'Test ON' and then 'System OK' or 'System NOT OK'. This is useful for verifying a fix or checking overall system readiness.
• VCDS (VAG-COM): Engine -> Output Tests — Allows for sequential testing of individual components. You can command the 'Secondary Air Injection (AIR) Pump Relay' to run the pump and also cycle the N112 solenoid to hear if it clicks, helping to isolate a failed electrical component without a cold start.

Wiring & Ground Locations

• Ground Point 13 — In the engine compartment, on the right side near the alternator.. This is a primary engine ground point. A corroded or loose ground here can cause a variety of electrical issues for engine-mounted components, including the SAI system's sensors and solenoids.
• N112 Solenoid Connector — On top of the engine near the throttle body.. This is the 2-pin connector for the vacuum solenoid. Pin 1 should receive 12V+ from the ECU, and Pin 2 is the control signal (grounded by the ECU to activate). Checking for voltage here is a key step if the solenoid is suspected to be faulty due to an electrical issue.

Real Owner Repair Stories

• Ross-Tech Forums user (Vehicle with P2440) — Check Engine Light with P2440 code. The issue only occurred when the ambient temperature was hot (above 80°F).
  ❌ Tried (didn't work) The user performed an output test on the combi valve, which seemed to function correctly., The user replaced the air pump and the hose assembly which included a new pressure sensor (G609).
  ✅ What actually fixed it The user reported the issue was not fully resolved but isolated it to a pressure/temperature-dependent problem. They suspected that when hot, the air pump was not producing enough pressure, causing the G609 sensor to send a voltage reading (3.3 VDC) that the ECU interpreted as a fault. This highlights a complex edge case where the valve itself is not the root cause.

OEM Part Supersession History

• 06E131101L → 06E131101M — Part revision by the manufacturer, likely for improved durability or material changes.
• Not specified, but 06E906517A is the current part. → 06E906517A — This part number is widely used across many VW/Audi models for both SAI and EVAP (N80) functions, indicating it is a standardized, reliable component.

Model Year Variations Within This Range

• 2012+: A connecting pipe between the two combi valves has a part number (06E131143AJ) that applies from production date 2/21/2012 onward, suggesting a potential minor design change in the plumbing around the time the C7 was fully rolled out.