Audi A5 Engine Coolant Temperature Sensor: A Guide for 2010-2015 Models
If your A5's temperature gauge is acting up or your fuel economy has dropped, your coolant sensor might be the culprit.
- Key symptoms include an erratic temperature gauge, poor fuel economy, rough idle, and a Check Engine Light, often with code P0118.
- For Audi electrical parts, it is wise to invest in a quality OEM-supplier brand like Hella, Delphi, or Vemo to ensure accuracy and longevity.
- Many 2.0T models have a separate, critical recall on the electric coolant pump that can pose a fire risk; this should be checked regardless of the sensor's condition.
- Replacement is a feasible DIY project for those comfortable working in tight spaces at the back of the engine.
Is Your Audi A5's Coolant Sensor Failing?
A failing Engine Coolant Temperature (ECT) sensor can cause a surprising number of problems in your 2010-2015 Audi A5. Because the sensor's readings affect so many engine functions, a bad signal can make your car run poorly long before you see the temperature gauge hit the red. Recognizing the signs early can save you from poor performance, bad fuel economy, and a check engine light.
Key Symptoms of a Bad ECT Sensor
- Check Engine Light: This is often the first sign. A common trouble code associated with a failing sensor is P0118 (Engine Coolant Temperature Sensor Circuit High). 🎬 See how to diagnose and fix a P0118 trouble code
- Erratic Temperature Gauge: The needle on your dashboard may jump around, read cold even after the engine has warmed up, or shoot to hot unexpectedly.
- Poor Fuel Economy: If the sensor incorrectly tells the ECU the engine is cold, the computer will enrich the fuel mixture, causing you to use more gas than necessary.
- Black Smoke from Exhaust: A consistently rich fuel mixture can result in unburnt fuel exiting through the exhaust, appearing as black smoke.
- Rough Idle or Hesitation: Your engine may shake, idle poorly, or hesitate during acceleration because the air-fuel mixture and ignition timing are incorrect.
- Cooling Fans Run Constantly or Not at All: The sensor is responsible for telling the fans when to turn on. A bad signal can cause them to run all the time, draining your battery, or not run when needed, risking overheating. 🎬 Watch: 8 common symptoms of a bad coolant sensor
Important Cooling System Recall for 2.0T Engines
There is a significant safety recall for the electric coolant pump (not the sensor) on many 2013-2017 Audi A5 models with the 2.0L TFSI engine. Debris can block this pump, causing it to overheat and creating a fire risk. Check with an Audi dealer or use your VIN on the NHTSA website to see if your vehicle is affected by recall 18V-229 (also listed as 19O2/19N4).
Choosing the Right Aftermarket Sensor
For many parts, aftermarket is a great way to save money. However, with German vehicles like your Audi A5, electrical components can be sensitive. While you don't necessarily need to buy a part from the dealer, choosing a quality aftermarket brand is important to avoid premature failure or inaccurate readings.
Based on owner experiences and mechanic recommendations, here is a general breakdown of brand quality for this part:
- Tier 1 (OEM Quality): Brands like Hella, Delphi, and Vemo are often Original Equipment Suppliers for Audi. These parts are expected to offer the same performance and longevity as the sensor your car came with from the factory.
- Tier 2 (Reliable Aftermarket): Brands such as Beck Arnley, Standard Ignition (SMP), and NGK have a solid reputation for producing dependable parts that meet or exceed OEM specifications.
- Tier 3 (Budget Options): Brands like Four Seasons and True Tech fall into the budget category. While they are the most affordable, some Audi owners report issues with budget electrical sensors, so the long-term reliability may be a concern.
Pro Tip: Check the Connector
Over the years, Audi has used different colors and connector shapes for these sensors. Before ordering, it's a good idea to visually inspect your current sensor to match the shape and pin count (it should be a 2-pin connector). Always replace the small O-ring seal at the same time to prevent coolant leaks.
Cost to Replace an Audi A5 Coolant Temperature Sensor
| Part Type | Estimated Cost |
|---|---|
| New OEM | $21 - $35 |
| New Aftermarket | $13 - $44 |
| Shop Labor | $135 - $200 |
| Total Estimated Cost (Shop) | $150 - $245 |
Frequently Asked Questions
Where is the engine coolant temperature sensor located on a 2010-2015 Audi A5?
On most A5s with the 2.0T engine, the primary ECT sensor (often designated G62) is located on a coolant flange on the back of the engine, near the firewall. Access is tight and may require removing an air intake hose to reach it. Some models may have a second sensor at the radiator outlet.
Is this a difficult DIY job?
For a moderately experienced DIYer, it is a manageable job. The part itself is simple to swap—it's usually held in by a plastic clip. The main challenge is the tight workspace. The job can take between 1 and 2 hours. 🎬 Watch this step-by-step 2.0L Turbo sensor replacement walkthrough You will lose a small amount of coolant, so have some G12/G13 coolant ready to top off the system.
Is a bad sensor the same as a bad thermostat?
No, they cause different issues. A bad thermostat is a mechanical part that often fails by getting stuck open. This will cause your engine to warm up very slowly and struggle to reach its normal operating temperature of 90°C (200°F). A bad sensor is an electrical failure that sends incorrect data, leading to a wider range of symptoms like a check engine light, poor fuel economy, and erratic gauge behavior.
Why does my outside temperature display seem slow to update?
This is normal. The *ambient* air temperature sensor (which is different from the engine coolant sensor) is programmed to update slowly to prevent incorrect readings from hot pavement or engine heat in stop-and-go traffic. This is not a sign of a faulty engine coolant sensor.
Helpful Videos
Technical Specifications
OEM Part Numbers: 06A919501A 05C919501 078919501C 059919501A
2-Pin Connector, O-Ring Seal
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 A5:
- 🎬 Helpful Videos
- 🛍️ Shop This Part
- Is Your Audi A5's Coolant Sensor Failing?
- Key Symptoms of a Bad ECT Sensor
- Important Cooling System Recall for 2.0T Engines
- Choosing the Right Aftermarket Sensor
- Pro Tip: Check the Connector
- Cost to Replace an Audi A5 Coolant Temperature Sensor
- Frequently Asked Questions
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