P2440 on 2011-2014 Audi S5: Secondary Air Injection Valve Stuck Open Causes & Fixes

What's Unique About the 2011-2014 Audi S5

The 2011-2014 S5 spans two different engines: the 4.2L V8 (2011-2012 Coupe, engine code CAUA) and the 3.0L Supercharged V6 (2013-2014 Coupe, 2011-2014 Cabriolet). While the P2440 code can occur on both, it is a well-documented and more frequent issue on the 3.0T engine, covered by a specific Technical Service Bulletin (TSB 01 16 73 2040403/3). The TSB provides a clear diagnostic path, pointing directly to either a bad combination ('combi') valve for a solitary P2440 code, or the N112 vacuum solenoid if P2440 and P2442 (Bank 2) appear together, making diagnosis more straightforward than on other vehicles.

Diagnostic Flowchart

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

Generation note: The 2011-2014 range covers the Audi S5 (B8.5) generation. However, a significant engine change occurred. The 2011-2012 Coupes used a 4.2L V8 (CAUA), while the 2013-2014 Coupes and all 2011-2014 Cabriolets used a 3.0L Supercharged V6. The TSB for P2440 specifically calls out the 3.0T engine, indicating the issue is more common and well-documented on the V6 models found not only in the S5 but also the S4, A6, A7, Q5, and Q7.

Symptoms You May Notice

• Check Engine Light (MIL) is on
• Vehicle will fail an emissions test
• Potential for rough running, hesitation, or stumbling, especially during slow acceleration from a stop.
• Audible whining or "vacuum cleaner" noise from the SAI pump for longer than the typical 30-90 seconds after a cold start.
• Often there are no noticeable performance issues other than the light.

Most Likely Causes

1. Defective Secondary Air Injection (Combi) Valve 🔴 High Probability The valve is exposed to high exhaust temperatures and moisture, which can cause internal corrosion or carbon buildup, causing it to stick open. This is a known issue acknowledged by Audi in TSB 01 16 73, which identifies it as the primary cause for an isolated P2440 code on the 3.0T engine.
   How to confirm: With the engine cold, start the car and feel for exhaust gas coming from the air pump inlet hose. Alternatively, apply vacuum to the valve with a hand pump; if it doesn't hold vacuum or you can hear it's not actuating with a 'click', it is defective. A forum user noted they could confirm a mechanical blockage by checking for dirt in the valve inlet where the air pipe connects.
   Typical fix: Replace the Bank 1 combination valve and the associated gasket.
   Est. part cost: $70-$200
2. Defective Vacuum Solenoid Valve (N112) 🟡 Medium Probability This solenoid controls the vacuum sent to both combi valves. It can fail electronically or get stuck, causing it to continuously send vacuum and hold the valves open. Audi's TSB identifies this as the primary cause if both P2440 and P2442 appear together. It is a common part across many VW/Audi vehicles.
   How to confirm: Check the vacuum lines at the combi valves on a cold start. If there is constant vacuum being supplied when the SAI system should be off, the solenoid is likely stuck open. The TSB provides the definitive diagnostic path: if P2440 is the only code that triggered the MIL, the combi valve is the cause; if P2440 and P2442 both triggered the MIL simultaneously, the solenoid is the cause. The solenoid can also be tested with a multimeter; its resistance should be between 25 and 35 ohms.
   Typical fix: Replace the vacuum solenoid valve, part number 037906283C.
   Est. part cost: $30-$90
3. Leaking or Disconnected Vacuum Hoses ⚪ Low Probability The plastic and rubber vacuum lines in the engine bay can become brittle over time due to heat cycles, leading to cracks and leaks. A crack in the vacuum line can lead to a loss of vacuum, preventing the combi valve from closing properly.
   How to confirm: Visually inspect all vacuum lines running from the solenoid to the combi valves for cracks, breaks, or loose connections. A smoke test can also be used to find small, hard-to-see leaks.
   Typical fix: Replace the damaged section of vacuum hose.
   Est. part cost: $10-$30

Rare But Worth Checking

• Clogged Secondary Air Injection Ports: This is a very common issue on the 3.0T and 3.2L engines but typically causes 'Insufficient Flow' codes (P0491/P0492), not 'Stuck Open' codes. There is a specific TSB for cleaning these carbon-clogged ports. While unlikely to cause P2440 directly, a complex system fault could be related. If you have replaced the valve and solenoid and still have issues, investigating the ports may be necessary.
🎬 Watch: How to handle carbon-clogged secondary air injection ports
• Faulty Engine Control Module (ECM): In very rare instances, a software glitch or a failing driver circuit in the ECM could cause the code. This should only be considered after all other mechanical and wiring possibilities have been exhausted. The primary TSB for this issue on the 3.0T points to a mechanical/electro-mechanical parts replacement, not a software update.

Diagnosis Steps

1. Read the fault codes with an OBD-II scanner. Note if P2440 is present alone or with P2442.
2. Refer to Audi TSB 01 16 73 2040403/3. If P2440 is the only code that triggered the MIL, suspect the Bank 1 combi valve. If P2440 and P2442 both triggered the MIL, suspect the vacuum solenoid.
3. Visually inspect the vacuum lines connected to the Bank 1 combi valve and the vacuum solenoid for any cracks, disconnections, or obvious damage.
4. To test the combi valve: With the engine cold, disconnect the large hose from the secondary air pump that leads to the combi valves. Start the engine. If you feel exhaust gas blowing out of the valve's inlet port, it is physically stuck open and must be replaced.
5. To test the vacuum solenoid: Locate the solenoid (often near the back of the engine). Check for vacuum at the line going to the combi valve when the system should be off (i.e., when the engine is warm or after the first ~90 seconds from a cold start). If vacuum is present, the solenoid is likely faulty and holding the valve open. Alternatively, test the solenoid's resistance with a multimeter; it should be between 25-35 Ohms.
6. If the valve and solenoid test good, perform a smoke test on the vacuum system to check for minor, hard-to-see leaks.
7. Check wiring to the solenoid for 12V power with the key on. If power is missing, check the associated fuse.

Parts You'll Likely Need

• Secondary Air Injection (Combi) Valve (OEM #06E131101E (for 3.0T), 079131101H (for 4.2L V8)) — This valve is the most common failure point for an isolated P2440 code, as identified in the manufacturer's TSB.
  Trusted brands: Genuine VW/Audi, Pierburg
  OEM price range: $150-$220
  Aftermarket price range: $70-$150
• Secondary Air Injection Vacuum Solenoid Valve (OEM #037906283C) — This is the primary suspect if both P2440 and P2442 codes are present. It controls the vacuum to both combi valves.
  Trusted brands: Genuine VW/Audi, Pierburg, Bosch, Febi
  OEM price range: $60-$90
  Aftermarket price range: $30-$60
• Combi Valve Gasket (OEM #078131120K (for 4.2L)) — This gasket seals the combi valve to its mounting point and should always be replaced when the valve is removed to prevent exhaust leaks. The TSB for the 3.0T also calls for a new seal and nut.
  Trusted brands: Genuine VW/Audi, Victor Reinz
  OEM price range: $5-$15
  Aftermarket price range: $2-$10

Related Codes That Often Appear With This One

• P2442 — This is the identical code but for Bank 2 (passenger side). According to Audi's TSB 01 16 73, if both P2440 and P2442 are present and triggered the MIL simultaneously, the root cause is almost certainly the single vacuum solenoid (N112) that controls both valves.

Technical Service Bulletins (TSBs) & Recalls

• 01 16 73 2040403/3: 'MIL on (DTC P2440(00) and/or P2442(00))' - The primary TSB for the 3.0T engine. States the cause is either a defective combi valve or a defective vacuum solenoid and provides the diagnostic logic.
• A011519 2040403-: The original TSB number, now superseded by 01 16 73.

Platform-Specific Known Issues

• Audi has issued Technical Service Bulletin 01 16 73 2040403/3 (superseding A011519) for the 3.0T engine, which explicitly states that DTC P2440 and/or P2442 are caused by either a defective combi valve or a defective vacuum solenoid. The TSB provides a clear flowchart: if only one code set the MIL, replace that bank's combi valve. If both codes set the MIL, replace the shared vacuum solenoid.

Mechanic-Grade Diagnostic Values

• N112 Vacuum Solenoid Electrical Resistance — expected: 25 - 35 Ohms. Failure: A reading significantly outside this range, or an open/short circuit, indicates a faulty solenoid.
• N112 Vacuum Solenoid Connector Voltage — expected: Battery Voltage (~12V) on one pin when the ignition is on.. Failure: No voltage suggests a problem with the fuse, relay, or wiring harness leading to the solenoid.

Scan Tool Commands That Help

• VCDS (VAG-COM) / ODIS: 01-Engine -> Output Tests (03) — This function allows a technician to cycle through and individually activate various engine components, including the Secondary Air Injection Solenoid (N112) and the SAI Pump Relay (J299). This is used to confirm if the ECM can command the components and if they respond with an audible click (solenoid) or by running (pump), which is crucial for diagnosis without a cold start.
• VCDS (VAG-COM) / ODIS: 01-Engine -> Basic Settings (04) -> Group 077 — On some VW/Audi models, this function initiates a complete self-test of the secondary air injection system. It runs the pump and checks for the expected change in oxygen sensor readings or pressure. This can be used to verify a repair or to check the system's overall health after replacing a component.

Wiring & Ground Locations

• Ground Point 12 — In the engine compartment on the left side, on the front long member (frame rail).. A poor ground at this location can cause intermittent electrical issues for various engine sensors and actuators, including the SAI system components. Verifying this ground is clean and tight is a fundamental step in diagnosing any electrical fault.
• N112 Solenoid Location — On the 3.0T engine, the N112 solenoid is located at the center rear of the engine, often mounted to a small tray or bracket under the small plastic engine cover.. Physical access is required to test the solenoid's resistance, check for voltage at its connector, and inspect the connected vacuum lines.
• SAI Pump (V101) Location — The SAI pump is typically located in the front lower corner of the vehicle, often behind the passenger or driver side front bumper cover and in front of the wheel well liner.. While not a direct cause of P2440, accessing the pump is necessary to check its hoses for moisture or carbon dust, which would indicate a failed combi valve has allowed exhaust backflow.

Real Owner Repair Stories

• Reddit user on r/Audi (2013 Audi S5, ~100,000 miles) — Check Engine Light with code P2440 appeared two days after a dealer visit.
  ❌ Tried (didn't work) The user did not report trying any fixes themselves before learning about the TSB.
  ✅ What actually fixed it The user was informed that a Technical Service Bulletin (TSB) exists for this specific code, which points to either the combi valve or the vacuum solenoid as the culprit, confirming the information in the official Audi documentation.

OEM Part Supersession History

• 06E131101E → 06E131101J, 06E131101K — Part revision and improvement by the manufacturer.
  Heads up: The newer revisions are expected to be direct replacements for the older part number on the 3.0T engine.