A Practical Guide to the Engine Coolant Temperature Sensor for the 2007-2012 Audi S6 V10
If your S6's temperature gauge is acting strange or your fuel economy has dropped, your coolant sensor might be the reason.
- The coolant sensor is critical for the S6 V10's performance, fuel economy, and cooling.
- Replacement is very difficult due to the sensor's location at the back of the engine against the firewall.
- Choose high-quality aftermarket brands that are OEM suppliers for German cars, like Hella or Vemo, for best results.
- Do not ignore symptoms like an erratic temperature gauge or Check Engine Light, as it could lead to engine damage from overheating.
Is Your S6 V10 Showing Signs of a Bad Coolant Sensor?
A failing Engine Coolant Temperature (ECT) sensor on the Audi S6 can cause a range of confusing problems. Because the sensor's reading is used for so many engine functions, a bad signal can make the car run poorly in several ways. The most common sign is a Check Engine Light on your dashboard. You might also notice your temperature gauge moving randomly, dropping to zero, or shooting up to max. Other symptoms include a noticeable drop in fuel mileage, black smoke from the exhaust, a rough idle, or the engine overheating because the radiator fans don't turn on when they should.
Choosing the Right Aftermarket Sensor for Your S6
The 5.2L V10 is a complex, high-performance engine. For critical electronic sensors, quality matters. While you can save money with an aftermarket part, it is wise to choose a brand known for supplying parts to German automakers.
- OEM-Supplier Brands (Recommended): Brands like Hella, Vemo, and Delphi are known for making high-quality sensors that meet or exceed original factory standards. These are your safest bet for reliability and a long service life, ensuring your V10 gets the accurate data it needs.
- Value Brands: Other brands like Beck Arnley, Four Seasons, and Standard Ignition offer more budget-friendly options. While they can be a good value, for a critical sensor on an engine this sensitive, sticking with an OEM-level brand is often worth the small extra cost for peace of mind.
Pro Tip: Before ordering, confirm the part number. The most common OEM part number is 059-919-501-A. Also, always get a new O-ring and retaining clip with your sensor, as the old ones are often brittle and should not be reused.
Known Issues, Recalls, and Bulletins
There are no active safety recalls from the NHTSA for the engine coolant temperature sensor on the 2007-2012 Audi S6. Audi has issued Technical Service Bulletins (TSBs) for the cooling system, such as one that addresses a "Cooling System Performance" fault code (P2181), but this was related to a broader engine computer software update, not a specific recall for the sensor itself. The failure of this sensor is a common maintenance item due to age and heat cycles.
Cost of Replacing the S6 Coolant Temperature Sensor
The cost is heavily influenced by the difficult labor. The sensor itself is not expensive, but getting to it is a challenge.
| Item | Estimated Cost |
|---|---|
| New OEM Sensor | $35 - $60 |
| New Aftermarket Sensor | $13 - $45 |
| Shop Labor | $300 - $500 |
| Total Estimated Cost (Professional) | $325 - $560 |
Costs are estimates and can vary by region and shop.
Frequently Asked Questions (FAQ)
Where is the coolant sensor located on the S6 V10?
The sensor is located on the back of the engine, tucked down between the engine block and the firewall. It is extremely difficult to see and reach, making replacement a challenging job even for experienced mechanics.
Can I replace this sensor myself?
This is not recommended for a beginner. The job requires working by feel in a very tight space. One Audi owner described it as "super hard to get at." You risk dropping the retaining clip or having trouble seating the new sensor and O-ring correctly, which can cause a coolant leak. If you are not comfortable with complex, frustrating jobs, it is best to leave this to a professional.
What happens if I ignore a bad coolant sensor?
You should not ignore it. Continuing to drive could lead to the engine running too rich, which wastes fuel and can damage your catalytic converters over time. More seriously, if the sensor fails to tell the computer the engine is overheating, the cooling fans may not turn on, leading to severe engine damage.
My mechanic is also recommending a new thermostat. Why?
The thermostat and the coolant sensor work together. A fault code like P0128, for example, can be caused by either a bad thermostat that is stuck open or a bad sensor. Since the labor to access these components can be high, a mechanic may suggest replacing both at the same time as a preventative measure, especially on an older vehicle.
Technical Specifications
OEM Part Numbers: 059919501A 05C919501
Typically a grey, 2-pin sensor. Always comes with a new O-ring and retaining clip.
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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.
- Audi S6: