GMC Acadia Engine Coolant Temperature Sensor Guide (2007-2017)
Diagnose and choose the right replacement engine coolant temperature sensor for your first-generation GMC Acadia.
- For 2017 models, confirm if you have the 'Limited' (old body style) or the new second-generation Acadia, as the sensor location and repair difficulty are vastly different.
- A faulty ECT sensor can cause a P0128 code, but so can a bad thermostat. Consider replacing both at the same time.
- When replacing the sensor, always inspect the wiring connector for signs of melting or heat damage from the nearby exhaust.
- On 2007-2016 models, this is a very simple DIY repair that can be done in minutes with basic tools.
Symptoms of a Failing ECT Sensor in a GMC Acadia
When the coolant temperature sensor starts to fail, it sends incorrect data to your Acadia's computer. This can cause a variety of confusing symptoms. You might see a Check Engine Light with codes like P0117, P0118, or P0119. A very common related code is P0128, which means the engine isn't reaching its proper operating temperature as quickly as the computer expects. This code can be caused by a bad thermostat or a faulty ECT sensor.
- Temperature Gauge Drops to Zero: The gauge on your dashboard may suddenly drop to cold, even when the engine has been running.
- Cooling Fans Run Constantly: As a fail-safe, the engine computer may run the cooling fans on high all the time to prevent potential overheating.
- Engine Overheating: Conversely, if the sensor fails to report a high temperature, the fans may not turn on when needed, leading to the engine overheating.
- A/C Stops Working: The climate control system may disable the A/C compressor if it receives a fault from the ECT sensor.
- "Steering Assist is Reduced" Message: On some Acadia models, a P0128 code can trigger this warning message as a precaution, even though the steering system itself is fine.
A Critical Note for 2017 Acadia Owners
The 2017 model year was a transition year for the GMC Acadia. If you own a 2017, you must identify which version you have. The older "Limited" model (first generation) has the easily accessible sensor described here. The new second-generation 2017 model has the sensor located in a very difficult-to-reach spot under the intake manifold, making replacement a much larger job.
Choosing the Right Aftermarket Sensor
For a simple but critical part like the ECT sensor, you don't have to buy from the dealer. However, quality varies between aftermarket brands. Here’s how they generally stack up for your Acadia.
| Brand Tier | Brands | Quality & Notes |
|---|---|---|
| OEM / Premium Aftermarket | ACDelco, Delphi, Bosch | ACDelco is the original GM parts supplier, so their parts offer a guaranteed fit and performance. Delphi and Bosch are also major OE manufacturers known for high-quality sensors that meet or exceed original specifications. Choosing from this tier is the safest bet. |
| Quality Aftermarket | NGK, Standard Ignition (SMP), Walker Products | These are reputable aftermarket brands with a long history of producing reliable parts. They offer a great balance of price and quality and are a solid choice for most repairs. |
| Economy / Store Brands | Duralast, Facet, Global Parts, etc. | These brands provide a cost-effective solution. While often perfectly functional, they may not have the same long-term durability or precise calibration as premium brands. They can be a good option if budget is the primary concern. |
Pro Tip: Inspect the Wiring
Due to its location near the exhaust manifold on the 2007-2016 models, the sensor's wiring connector can sometimes melt or become brittle. When you replace the sensor, carefully inspect the plastic connector and wires for any signs of heat damage. A new connector pigtail is available if needed.
Frequently Asked Questions
Should I replace the thermostat with the ECT sensor?
If your Acadia is setting a P0128 code, it's often a good idea to replace the thermostat at the same time as the ECT sensor. The thermostat is a common failure point that causes this code. Since you're already working in the cooling system, replacing both can save you from having to do a similar job twice.
🎬 See how to replace the thermostat to clear a P0128 code.Where is the ECT sensor located on my 2007-2016 Acadia?
On the 3.6L V6 engine used from 2007-2016, the sensor is conveniently located on the front of the engine, just below and to the left of the oil dipstick tube. 🎬 Watch this step-by-step guide to replacing the sensor yourself. It is easily accessible after removing the plastic engine cover, making this a great DIY-friendly repair.
Is it hard to replace the ECT sensor on my Acadia?
For 2007-2016 models, it is a very easy job. It requires minimal tools (a deep 19mm or 3/4" socket) and can be done in under 30 minutes. For the new-body 2017 model, it is a very difficult job that may require removing the intake manifold.
Why did my dash say "Steering Assist is Reduced"?
This is a strange side effect of the P0128 trouble code. The computer links engine temperature to the power steering system's operating parameters. When it detects an engine temperature fault, it displays the steering message as a precaution to get your attention. Fixing the coolant temperature issue will resolve the steering message.
🎬 Watch how to fix the 'Steering Assist is Reduced' warning.Helpful Videos
Technical Specifications
OEM Part Numbers: 12639899 213-4777 12650595
Location (2007-2016): Front of engine, by oil dipstick tube. Location (2017+ New Body): Near thermostat housing, under intake manifold. Tool needed: 19mm or 3/4" deep socket.
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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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