A Guide to the Boost Pressure Sensor for the 2010-2016 Audi S4
Is your supercharged S4 feeling sluggish or throwing a check engine light? A faulty boost pressure sensor could be the reason.
- This sensor measures pressure from your S4's supercharger, even though it's often mislabeled as a 'turbocharger' sensor.
- Bosch is an OEM supplier, making their aftermarket sensor a high-quality, reliable replacement without the dealership price tag.
- Before replacing the sensor, check the wiring harness for damage, as a TSB indicates this is a known issue causing identical symptoms.
- Your S4 has two of these sensors; you only need to replace the one that has failed.
Understanding the Boost Pressure Sensor in Your S4
The B8 and B8.5 generation Audi S4 (2010-2016) is known for its powerful supercharged 3.0T V6 engine. A key component in managing this power is the boost pressure sensor. It's a small but vital part that ensures your engine performs as expected. When it fails, you'll notice significant issues with how your car drives. It's important to note that while this part is often listed as a "Turbocharger Boost Sensor," your S4 has a supercharger; the sensor's function of measuring boost pressure is the same.
Symptoms of a Failing Boost Pressure Sensor
A bad boost pressure sensor can cause a range of problems, from annoying to serious. Here are the most common signs that your sensor may need replacement:
- Check Engine Light: This is often the first sign. You may see codes like P0236, P0237, or P0238, which point to a problem with the boost sensor circuit.
- Loss of Power: Your S4 will feel noticeably slower and less responsive, especially when you try to accelerate hard.
- Poor Fuel Economy: The engine's computer can't properly calculate the air-fuel mixture, often leading to the engine running too rich and wasting fuel.
- Rough Idle or Surging: The engine may idle unevenly or surge during acceleration because of incorrect sensor readings.
Known Issues & TSBs
Audi has issued a Technical Service Bulletin (TSB) for some vehicles that experience boost sensor-related fault codes (like P0234, P0235, P0236, P0237, P0238). The TSB notes that the engine wiring harness near the sensor can be too tight, causing the wires or pins in the connector to break or pull out. Before replacing the sensor, it's a good idea to inspect the wiring and connector for any visible damage, as this could be the actual root cause of the problem.
Choosing the Right Aftermarket Boost Sensor
When replacing the boost pressure sensor on your S4, you have a choice between OEM and aftermarket parts. For this specific component, the decision is straightforward.
- OEM (Original Equipment Manufacturer): This is the part you would get from an Audi dealership. It's a guaranteed fit and quality, but it comes at a higher price.
- Bosch Aftermarket: Bosch is a well-respected brand that is often the original equipment manufacturer for many Audi parts. This means the aftermarket Bosch sensor is typically identical to the OEM part in quality and performance, but available at a lower cost. For the 2010-2016 S4, choosing a Bosch aftermarket sensor is a reliable and cost-effective option.
Pro Tip: The 3.0T engine in your S4 has two of these sensors, one on each side of the supercharger. They are mirror images of each other. If one fails, it's wise to inspect the other, though you typically only need to replace the one that has failed.
Cost of Replacing an Audi S4 Boost Pressure Sensor
| Part Type | Estimated Cost |
|---|---|
| New OEM | $150 - $225 |
| New Aftermarket (Bosch) | $41.46 - $62.05 |
| Shop Labor | $50 - $75 |
Frequently Asked Questions (FAQ)
Can I drive my S4 with a bad boost pressure sensor?
You can, but it's not recommended. The vehicle may enter a reduced power or "limp mode" to protect the engine. You will experience poor performance, bad fuel economy, and could potentially cause further issues if ignored for too long.
Is this a difficult part to replace myself?
No, for a DIYer with basic tools, this is a relatively easy job. The sensors are located on the sides of the supercharger and are accessible after removing the engine cover. Each sensor is held in by one Torx screw and an electrical connector. The entire process should take less than an hour.
Are there any recalls for this part on my S4?
As of early 2026, there are no specific recalls issued by the NHTSA for the boost pressure sensor on the 2010-2016 Audi S4. However, a TSB exists regarding the wiring harness, which can cause the same symptoms.
Do I need to replace both sensors at the same time?
It is not required to replace both sensors simultaneously. You only need to replace the sensor that has failed and is causing the fault code. However, since they are the same age, the other sensor may fail in the future.
Technical Specifications
OEM Part Numbers: 038906051C 03G906051M 038906051J 03C906051F
The 2010-2016 Audi S4 3.0T uses two boost pressure sensors, one on each side of the supercharger assembly. They are 4-pin sensors that measure absolute pressure in the intake tract after the supercharger.
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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.
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