Lincoln MKZ Engine Coolant Temperature Sensor: A Complete Guide for 2007-2020 Models
Solve overheating, poor mileage, and check engine lights by choosing the right replacement sensor for your Lincoln MKZ.
- A failing ECT sensor can cause a Check Engine Light, poor fuel economy, overheating, and rough idling.
- For code P0128, the cause is often a stuck-open thermostat, not the sensor itself.
- Replacement difficulty varies drastically by engine: it is very easy on the 2.0L but extremely difficult on the 3.5L/3.7L V6.
- For this critical part, it is highly recommended to use the OEM Motorcraft sensor or a premium aftermarket brand like Delphi or NGK.
Symptoms of a Failing ECT Sensor in a Lincoln MKZ
When the Engine Coolant Temperature (ECT) sensor starts to fail, it can send wrong information to your car's computer, causing a variety of problems. Here are the most common signs MKZ owners experience:
- Check Engine Light: This is often the first sign. The computer will log a fault code, such as P0117 (sensor circuit low/too hot), P0118 (sensor circuit high/too cold), or P0128 (engine not reaching operating temperature).
- Poor Fuel Economy: If the sensor wrongly tells the computer the engine is always cold, the computer will enrich the fuel mixture, causing you to use more gas than necessary.
- Engine Overheating: A faulty sensor might fail to report that the engine is getting too hot. This can prevent the radiator fans from turning on, leading to overheating and potential engine damage.
- Black Smoke from Exhaust: An overly rich fuel mixture, caused by a false 'cold' signal, may not burn completely. This unburnt fuel can exit the tailpipe as black smoke.
- Rough Idle or Stalling: The wrong fuel mixture can make your engine run poorly, especially when idling. It may stumble, hesitate, or even stall.
- Erratic Temperature Gauge: The temperature gauge on your dashboard might swing back and forth, stay on cold, or jump straight to hot.
Known Issues for 2017-2019 Lincoln MKZ 2.0L EcoBoost Engines
A class-action lawsuit was filed concerning some 2017-2019 MKZ models with the 2.0L EcoBoost engine. The lawsuit alleges a design issue can allow coolant to leak into the engine's cylinders, which can lead to coolant loss, overheating, and major engine failure. While not a sensor failure, if you have one of these models and are experiencing coolant loss or overheating, this is an important issue to be aware of.
🎬 Watch: Understanding the EcoBoost coolant intrusion and block crack issue.Choosing the Right Aftermarket Sensor
With many brands available, picking the right one is important for a lasting repair. For a critical part like the ECT sensor, quality matters. An inaccurate sensor can negatively affect performance and fuel economy.
- OEM (Motorcraft): Ford's own brand, Motorcraft, is the original part your MKZ was built with. It is the benchmark for fit and accuracy and is recommended for guaranteed compatibility.
- Premium Aftermarket (Delphi, NGK/NTK, Standard Ignition): These brands have a strong reputation for producing high-quality parts that meet or exceed OEM specifications. Delphi, for example, is known for its robust, one-piece sensor design that eliminates common failure points. They are a reliable choice if you want OEM quality without the dealer price tag.
- Standard Aftermarket (Four Seasons, Walker Products, Holstein): These brands offer a good balance of value and quality. They are a popular choice for many repairs and generally perform well.
- Budget Brands (Global Parts, True Tech, Facet): These are typically the most affordable options. While they can work, they may not have the same level of testing or material quality as premium brands, which could lead to a shorter lifespan or less precise readings.
Pro Tip: For a critical sensor like this, spending a few extra dollars on a Motorcraft, Delphi, or NGK sensor is a wise investment to avoid potential performance issues or having to do the job twice.
Replacement Cost for a Lincoln MKZ ECT Sensor
The cost depends heavily on your engine and whether you do it yourself or hire a mechanic.
| Item | Cost Range |
|---|---|
| New Aftermarket Part | $10.99 - $63.18 |
| New OEM (Motorcraft) Part | $27.00 - $48.00 |
| Shop Labor | $95 - $450+ |
| Estimated Total (Shop Repair) | $125 - $500+ |
Labor costs vary dramatically based on which engine your MKZ has. See the installation section below.
Installation: A Tale of Two Difficulties
The difficulty of replacing the ECT sensor on a Lincoln MKZ depends entirely on the engine.
- 2.0L, 2.5L, and 3.0L Engines: On these engines, the sensor is generally accessible. For example, on the 2.0L Hybrid, the sensor is located on top of the engine between two ignition coils. On the 3.0L, it is often in or near the thermostat housing. Replacement is feasible for a DIYer with basic tools.
Warning for 3.5L and 3.7L V6 Engine Owners
On the 3.5L and 3.7L V6 engines, the ECT sensor is in an extremely difficult-to-reach location. It is on the rear cylinder head, underneath the lower intake manifold. Replacing it requires removing the entire upper and lower intake manifold assembly. This is a complex and time-consuming job (4+ hours) and is not recommended for most DIY mechanics.
🎬 See this walkthrough for the difficult V6 sensor replacement.Frequently Asked Questions
Where is the engine coolant temperature sensor located on my MKZ?
It varies by engine. On 2.0L Hybrid models, it's on top of the cylinder head between coils 3 and 4. On 3.5L/3.7L V6 models, it's buried under the intake manifold on the rear cylinder head. On other engines, it is typically screwed into the thermostat housing or the cylinder head near a coolant passage.
How many ECT sensors does my Lincoln MKZ have?
Most MKZ models have one primary ECT sensor that reports to the computer. However, some hybrid models may have a second sensor on the heater core lines to monitor temperatures for the hybrid system. Ford also uses a Cylinder Head Temperature (CHT) sensor on some engines, which serves a similar but distinct purpose.
Can a bad thermostat cause the same problems?
Yes. A thermostat that is stuck open is a very common cause for the P0128 trouble code. This is because the coolant constantly circulates through the radiator and the engine never reaches its proper operating temperature. If you have a P0128 code, it is often recommended to inspect or replace the thermostat first, as it is a more common failure point than the sensor itself.
🎬 Watch: How to fix P0128 codes by replacing the thermostat.What do the check engine codes for the ECT sensor mean?
The codes point to a specific type of failure. P0117 indicates the computer is seeing a voltage that is too low, which it interprets as an extremely high temperature. P0118 is the opposite, a voltage that is too high, interpreted as an extremely low temperature. P0128 means the computer has determined the engine isn't warming up as quickly as it should, often due to a stuck thermostat or a faulty sensor.
Helpful Videos
Technical Specifications
OEM Part Numbers: FT4Z-12A648-B 3F1Z-12A648-A 3L8Z-12A648-A 7M5Z-12A648-A AU5Z12A647B DY1143 DY1309
The Engine Coolant Temperature sensor is a thermistor, meaning its electrical resistance changes with temperature. It typically has a 2-pin rectangular electrical connector.
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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.
- Lincoln MKZ:
- 🎬 Helpful Videos
- 🛍️ Shop This Part
- Symptoms of a Failing ECT Sensor in a Lincoln MKZ
- Known Issues for 2017-2019 Lincoln MKZ 2.0L EcoBoost Engines
- Choosing the Right Aftermarket Sensor
- Replacement Cost for a Lincoln MKZ ECT Sensor
- Installation: A Tale of Two Difficulties
- Warning for 3.5L and 3.7L V6 Engine Owners
- Frequently Asked Questions
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