1990-1991 Lexus ES250 Coolant Temperature Sensor Guide
If your classic ES250 is running poorly or getting bad gas mileage, the engine coolant temperature sensor is a common and affordable part to check.
- A bad coolant sensor on your ES250 can cause poor fuel economy, rough running, and overheating.
- This vehicle has two coolant sensors; ensure you are replacing the two-wire sensor for the engine computer, not the one-wire sender for the gauge.
- Replacement is a simple, DIY-friendly task that can be completed in under an hour with basic tools.
- An aftermarket sensor is a cost-effective and reliable choice for this repair on a 1990-1991 ES250.
Is Your ES250 Running Poorly? It Could Be the Coolant Sensor
When the Engine Coolant Temperature (ECT) sensor on your 1990-1991 ES250 fails, it sends incorrect information to the engine's computer. This can lead to a variety of noticeable issues. Because this is an older vehicle, it's important to address these symptoms to prevent poor performance or more serious engine problems. Common signs of failure include a Check Engine Light, poor fuel economy, black smoke from the exhaust, and rough idling.
Two Different Coolant Sensors
Your ES250 has two separate sensors for coolant temperature. One is a single-wire sender used only for the temperature gauge on your dashboard. The other is a two-wire ECT sensor that sends critical data to the engine computer (ECU). This guide focuses on the two-wire ECT sensor that affects engine performance. Make sure you are diagnosing and replacing the correct part for the symptoms you are experiencing.
Choosing the Right Aftermarket Sensor
For a vehicle like the 1990-1991 ES250, a new aftermarket coolant temperature sensor provides a reliable and cost-effective solution. While some owners prefer to use original equipment (OEM) parts for all electronic sensors, quality aftermarket brands are a dependable choice for this repair. Given the straightforward function of this sensor and the age of the vehicle, an aftermarket part from a reputable manufacturer meets the needs of most owners without the higher cost of an OEM part. 🎬 Watch this comparison of OEM versus aftermarket engine sensors. The key is to ensure the part has the correct two-pin connector for the ECU sensor.
Check the Connector Before You Buy
Before ordering a new part, it's a good idea to look at the sensor in your car. The correct ECT sensor for the ECU on the ES250 has a two-pin (two-terminal) electrical connector. The sensor for the temperature gauge only has one wire. Verifying the connector shape and pin count helps ensure you order the right part the first time.
Known Issues, Recalls, or TSBs
Searches of the National Highway Traffic Safety Administration (NHTSA) database show no specific recalls or Technical Service Bulletins (TSBs) for the engine coolant temperature sensor on the 1990-1991 Lexus ES250. Any recalls listed for this vehicle are for unrelated components like suspension parts.
Cost to Replace the ES250 Coolant Temperature Sensor
Replacing this sensor is an affordable repair. The part itself is inexpensive, and if you take it to a shop, the labor time is typically less than an hour.
| Item | Estimated Cost |
|---|---|
| New Aftermarket Part | $19.57 |
| Shop Labor | $50 - $100 |
| Total Estimated Cost | $70 - $120 |
Frequently Asked Questions (FAQ)
Where is the coolant temperature sensor located on a 1990-1991 ES250?
The ECT sensor for the ECU is located on the thermostat housing (also called the water outlet), near where the upper radiator hose connects to the engine. It is a two-wire sensor. Do not confuse it with the single-wire sender for the dashboard gauge, which is located in a different spot.
Can I replace this sensor myself?
Yes, this is a very DIY-friendly job for a home mechanic with basic tools. The process involves letting the engine cool completely, partially draining some coolant, unplugging the electrical connector, and using a deep socket wrench to unscrew the old sensor and install the new one. Topping off the coolant is the final step.
What happens if I don't replace a bad coolant sensor?
Ignoring a faulty ECT sensor can lead to persistent issues like very poor fuel economy, failed emissions tests, and rough engine performance. In a worst-case scenario, it could prevent the cooling fans from turning on correctly, which can cause the engine to overheat and lead to severe damage like a blown head gasket.
What are the common trouble codes for a bad coolant sensor?
A failing coolant temperature sensor can trigger the Check Engine Light. Common diagnostic trouble codes (DTCs) associated with this sensor's circuit include P0115, P0117, and P0118.
Helpful Videos
Technical Specifications
OEM Part Numbers: 8942220010 89422-20010 8342016010 8342020020
Typically a 2-pin/2-terminal sensor that threads into the engine's water outlet housing.
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.
- Lexus ES250: