Audi A8 Quattro Secondary Air Injection Pump: A Guide for 2011-2018 Models
Understanding the common 'jet engine' noise on cold starts and how to fix it correctly.
- A loud 'jet engine' noise on cold start is the classic symptom of a failing pump motor.
- Insufficient flow codes (P0491, P0492) are often caused by bad check valves or clogged ports, not the pump itself.
- Hella is an OEM-quality supplier for this part, offering a reliable repair without the high dealer price tag.
- You can drive with a bad pump, but the Check Engine Light will stay on and you will fail an emissions test.
Symptoms of a Failing Audi A8 Secondary Air Injection Pump
When the secondary air injection pump starts to fail on your 2011-2018 A8 Quattro, the signs are usually very distinct. Being aware of them can help you diagnose the problem before you start buying parts.
- Loud Noise on Cold Starts: The most common symptom is a loud whining, howling, or "vacuum cleaner" sound coming from the front passenger side of the engine bay when you first start the car. This noise typically lasts for a minute or two and then disappears as the pump shuts off. This is caused by the internal bearings of the pump motor wearing out.
- Check Engine Light: The engine's computer monitors the SAI system. If it detects a problem, like an incorrect amount of airflow, it will trigger the Check Engine Light. You will likely see diagnostic trouble codes (DTCs) such as P0411, P0491, or P0492. 🎬 See how to diagnose these specific Audi fault codes.
- Failed Emissions Test: Because this is an emissions-related part, a failure will cause your vehicle to fail a state emissions inspection. Many owners only discover the problem during a required test.
Diagnose Before You Replace
The fault codes P0491 and P0492 (Insufficient Flow) do not automatically mean the pump is bad. On these Audi engines, these codes are often caused by other issues in the system. A faulty one-way check valve (combi valve) can allow moisture and hot exhaust gas to flow backward into the pump, destroying it. Also, clogged air passages in the cylinder head are a known issue that can restrict airflow and trigger a code. Always inspect the entire system for bad relays, blown fuses, cracked hoses, or faulty check valves before replacing the pump itself.
Choosing the Right Aftermarket Pump for Your A8
When it comes to replacing the SAI pump, you have a few options. Understanding the difference can save you money and ensure a lasting repair.
- OEM (Original Equipment Manufacturer): These are the parts you would get from an Audi dealership. They are guaranteed to fit and function correctly but are the most expensive option.
- OEM Supplier (Hella/Pierburg): Brands like Pierburg are often the original manufacturer for Audi's parts. Hella distributes these same Pierburg pumps. Choosing a Hella or Pierburg pump gives you the exact same quality and performance as the dealer part, but without the Audi logo and at a significantly lower cost. This is the recommended choice for both quality and value.
- Aftermarket: There are other, cheaper aftermarket brands available. While tempting, their quality, fitment, and durability can be inconsistent. For a critical emissions component on a high-performance vehicle like the A8, it is generally best to stick with an OEM supplier like Hella.
| Part Type | Estimated Cost |
|---|---|
| New OEM (Audi Dealer) | $500 - $850 |
| New Aftermarket (Hella) | $474.93 |
| Used OEM | $100 - $250 |
| Shop Labor | $200 - $400 |
Pro Tip: Replace the Combi Valve
The most common reason for SAI pump failure is a bad combi valve that lets moisture into the pump. If you replace the pump but not the faulty valve, the new pump will likely fail for the same reason. It is highly recommended to inspect and, if necessary, replace the combi valve(s) at the same time as the pump to ensure a long-lasting repair.
🎬 Watch why these pumps fail and how to prevent it.Frequently Asked Questions (FAQ)
Can I drive my Audi A8 with a bad secondary air pump?
Yes, you can safely drive the vehicle. The pump's failure does not affect the engine's primary performance or reliability once it's warm. However, your Check Engine Light will stay on, and you will not be able to pass an emissions test until it is repaired.
Where is the secondary air injection pump located on the 2011-2018 Audi A8?
The secondary air injection pump is typically located on the front passenger side of the vehicle, behind the fender liner. Accessing it requires lifting the vehicle and removing the front passenger-side wheel and the plastic fender liner. Do not confuse it with the air suspension compressor, which is a different system.
Is it difficult to replace the SAI pump myself?
For a DIYer with the right tools, it is a moderately difficult job. It involves safely lifting the car, removing the wheel and fender liner, and working in a somewhat tight space to unbolt the pump and disconnect its hoses and electrical connector. The difficulty rating is about a 3 out of 5.
🎬 Watch this step-by-step guide to replacing the pump yourself.Can I just remove or delete the SAI system?
Physically removing the system will cause a permanent Check Engine Light and guaranteed emissions test failure. While some choose to have the system 'coded out' of the engine's computer with a custom tune, this is not legal for road use in many areas and can complicate future diagnostics. For most owners, repairing the system is the best option.
Helpful Videos
Technical Specifications
OEM Part Numbers: 079959253 07L959231 079959231L 079959231C 079959231A
This is an electric air pump that operates on the vehicle's 12V system. It is controlled by the engine computer via a relay and typically runs for 30-90 seconds on cold start only.
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Audi A8 Quattro: