GMC K2500 Engine Coolant Temperature Sensor Guide (1995-2000)
A failing coolant temperature sensor can cause poor fuel economy and running issues in your K2500.
- Verify if you need the two-wire ECT 'sensor' for the computer or the one-wire 'sender' for the gauge.
- A bad ECT sensor directly impacts fuel economy and engine performance; it's not just a gauge issue.
- This is a simple, low-cost DIY repair that can solve significant running problems.
- Stick to trusted aftermarket brands like Delphi, NGK/NTK, or Standard Ignition for reliability.
Is Your K2500 Running Rough or Getting Bad Gas Mileage?
Before you suspect more complex issues, it's worth checking the Engine Coolant Temperature (ECT) sensor. This small, inexpensive part plays a huge role in how your engine performs. A faulty sensor can send incorrect information to your truck's computer, leading to a variety of problems that can seem much bigger than they are. Ignoring a bad ECT sensor can lead to poor fuel economy, failed emissions tests, and long-term engine strain.
Symptoms of a Failing ECT Sensor
If the ECT sensor on your K2500 is going bad, you'll likely notice one or more of the following signs:
🎬 Watch a breakdown of common symptoms and signs of failure.- Check Engine Light: This is often the first sign. The computer will store trouble codes like P0117 (Circuit Low Input) or P0118 (Circuit High Input).
- Poor Fuel Economy: If the sensor incorrectly tells the computer the engine is always cold, the computer will continuously run a rich fuel mixture, wasting gas.
- Black Smoke from Exhaust: A rich fuel mixture that isn't burning completely can exit the tailpipe as black smoke.
- Hard Starting: The engine may be difficult to start, especially when it's already warm, because the fuel mixture is incorrect.
- Rough Idle: An incorrect fuel mixture can cause the engine to idle roughly or stall.
- Engine Overheating: While less common, if the sensor fails to signal that the engine is hot, the electric cooling fans may not turn on when needed.
Pro Tip: Sensor vs. Sender
Your 1995-2000 K2500 likely has two temperature-related parts. The Engine Coolant Temperature Sensor has a two-wire connector and sends information to the engine computer. It is usually located on the front of the intake manifold near the thermostat housing on V8 gas engines. The Coolant Temperature Sender has a one-wire connector and only operates the gauge on your dashboard. It is often located on the side of the cylinder head. Make sure you are replacing the correct part for the symptoms you are experiencing.
Choosing the Right Aftermarket ECT Sensor
For a vehicle like the 1995-2000 K2500, a quality aftermarket sensor is a reliable and cost-effective choice. The original equipment (OEM) brand is ACDelco. However, many aftermarket brands offer excellent quality, sometimes from the same factory that made the original part.
- Top-Tier Aftermarket (OEM Equivalent): Brands like Delphi and NGK (NTK) are excellent choices. Delphi was an original parts supplier for GM, so their parts are often identical to the ACDelco part. NGK/NTK is a world-renowned sensor manufacturer with a strong reputation for quality.
- Quality Mid-Range Aftermarket: Brands like Standard Ignition (SMP), Beck Arnley, and Hella offer a great balance of price and performance. They are trusted names in the aftermarket and produce reliable sensors.
- Economy Options: Brands like Four Seasons, Walker Products, and others can be a good value, but quality can be less consistent. For a critical sensor like the ECT, it's often worth spending a few extra dollars for a more trusted brand to avoid premature failure and drivability issues.
A Note on Recalls and TSBs
As of early 2026, there are no specific recalls or Technical Service Bulletins (TSBs) from GMC or the NHTSA directly concerning the engine coolant temperature sensor for the 1995-2000 K2500. Any issues are typically due to normal wear and tear on the part.
Typical Replacement Costs
Replacing the ECT sensor is one of the more affordable repairs you can perform on your truck.
| Part Type | Estimated Cost |
|---|---|
| New Aftermarket Sensor | $12 - $38 |
| New OEM (ACDelco) Sensor | $25 - $50 |
| Shop Labor | $50 - $100 |
| Total DIY Cost | $12 - $38 |
| Total Shop Cost | $62 - $150 |
Frequently Asked Questions (FAQ)
Is it hard to replace the ECT sensor on a K2500?
No, this is a very DIY-friendly job. On most V8 gas engines, the sensor is easily accessible on the front of the intake manifold. The job requires basic hand tools, takes less than an hour, 🎬 See how to replace the sensor on a GMC K-series truck. and involves draining a small amount of coolant.
Where is the ECT sensor located on my K2500?
For gasoline V8 engines (5.7L, 7.4L), the main ECT sensor is typically threaded into the front of the intake manifold, near the thermostat housing. 🎬 Follow this guide for replacing the thermostat and sensor together. The separate, single-wire gauge sender is often in the driver's side cylinder head. Always verify the location on your specific engine before beginning work.
Can I drive my truck with a bad ECT sensor?
You can, but it's not recommended for long. A bad sensor can cause poor engine performance, terrible fuel economy, and potentially lead to the engine overheating or fouling the spark plugs and catalytic converter over time.
Do I need to drain all the coolant to replace the sensor?
You don't need to drain the entire system. You can drain just a gallon or so from the radiator's drain petcock until the coolant level is below the sensor. Some coolant will still spill when you remove the old sensor, so have a rag ready.
Helpful Videos
Technical Specifications
OEM Part Numbers: 15326386 25036979
The ECT sensor for the ECM typically has a two-pin Metri-Pack 150.2 style connector. The gauge sender has a single spade or threaded stud connector. The main sensor is usually located on the intake manifold near the thermostat housing.
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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.
- GMC K2500: