Engine Coolant Temperature Sensor Guide for the 2019-2023 Lexus IS350
Is your IS350 running rough or getting poor gas mileage? A faulty coolant temperature sensor could be the culprit.
- A bad ECT sensor on your IS350 will most likely cause a Check Engine Light with codes P0117, P0118, or P0128.
- Symptoms directly impact drivability, including poor fuel economy, rough idling, and a risk of overheating.
- There are no known recalls for this specific part; failures are typically due to age and wear.
- For best results, choose a quality aftermarket brand like Delphi or Walker Products to ensure accurate readings.
Is Your IS350's Engine Coolant Temp Sensor Failing?
A bad Engine Coolant Temperature (ECT) sensor can cause a surprising number of problems in your 2019-2023 Lexus IS350. Because the sensor's reading affects so many engine functions, a wrong signal can lead to poor performance and even potential engine damage. Watch for these common signs.
Key Failure Symptoms:
- Check Engine Light: This is often the first sign. A scanner will likely show codes like P0117, P0118, or P0128.
- Poor Fuel Economy: If the sensor wrongly tells the computer the engine is cold, the system will use more fuel than needed.
- Engine Overheating: A faulty sensor may fail to signal the cooling fans to turn on, causing the engine to overheat, especially in traffic.
- Rough Idle or Sluggish Performance: The wrong fuel mixture can make the engine run poorly, shake at idle, or feel hesitant when you accelerate.
- Black Smoke from Exhaust: This is a sign of an overly rich fuel mixture, where unburned fuel is exiting through the exhaust.
Don't Ignore the Signs
While you can drive with a faulty ECT sensor, it's not recommended for long. Continuing to drive could lead to poor fuel efficiency, failed emissions tests, and a risk of severe engine damage from overheating.
Choosing the Right Aftermarket Sensor for Your IS350
When replacing the ECT sensor on your Lexus, you have a choice between OEM and aftermarket parts. For a vehicle like the IS350, quality matters. The OEM sensor is often made by Denso, a brand known for its reliability. However, high-quality aftermarket brands can offer similar performance for less money.
Aftermarket Brand Tiers
- Top Tier (OEM-Level Quality): Brands like Delphi fall into this category. Delphi is a well-respected manufacturer that is often an Original Equipment supplier for many car brands. They are known for producing reliable sensors that meet or exceed factory specifications.
- Mid-Tier (Reliable Aftermarket): Walker Products is an established aftermarket brand with a long history. They engineer their parts to match original fit and function and perform extensive testing, making them a solid and dependable choice for your Lexus.
- Value Tier (Budget-Friendly): Brands like Global Parts typically represent the most affordable option. While they can get the job done, there is less public data and fewer reviews on their long-term reliability compared to more established brands. This tier is best for those on a tight budget who need a functional replacement.
Pro Tip: For a critical component like the ECT sensor, spending a little more for a top-tier aftermarket brand like Delphi can provide peace of mind and performance similar to the original factory part.
Cost to Replace the Lexus IS350 ECT Sensor
The cost can vary significantly between doing it yourself and having a shop perform the work. The sensor's location on the 3.5L V6 engine can be difficult to access, leading to higher labor charges.
| Part/Service | Estimated Cost |
|---|---|
| New OEM Part | $75 - $220 |
| New Aftermarket Part | $21 - $85 |
| Shop Labor | $380 - $680 |
| Total Professional Replacement | $401 - $900 |
Frequently Asked Questions (FAQ)
Are there any recalls for the IS350 coolant temperature sensor?
No. As of early 2026, there are no specific recalls or widespread Technical Service Bulletins (TSBs) from Lexus or the NHTSA for the engine coolant temperature sensor on the 2019-2023 IS350. Major recalls for this model concern the fuel pump assembly.
Can I replace the ECT sensor myself?
Yes, it is possible for a DIYer with moderate experience. However, the sensor is located under the air intake and near the firewall, requiring the removal of several components like the battery and intake snorkel for access. You will need tools like a deep 19mm socket, extensions, and a swivel joint. Due to the difficult access, many owners may prefer to have a professional handle the replacement.
What do the trouble codes P0117 and P0128 mean?
These are common codes related to a bad ECT sensor. P0117 (Circuit Low Input) means the ECU is seeing a voltage signal that is too low, which it interprets as an extremely high engine temperature. P0128 (Coolant Temperature Below Thermostat Regulating Temperature) means the ECU has determined the engine is not warming up as quickly as it should, which can be caused by a faulty sensor or a stuck-open thermostat.
How many coolant temperature sensors does the IS350 have?
Most modern vehicles, including the IS350, primarily use one main ECT sensor to provide data to the engine computer for managing fuel, spark, and cooling fans. Some systems may have a second sensor or switch specifically for the temperature gauge on the dashboard or for the radiator fans, but the one that triggers engine performance issues and fault codes is the main ECT sensor connected to the ECU.
Technical Specifications
OEM Part Numbers: 89422-33030 89422-33040 89422-47010
The sensor is a thermistor type, typically with a 2-pin connector, that threads into the engine's coolant passages near the thermostat housing.
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.
- Lexus IS350: