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Lexus GS450h (2007-2018) Engine Coolant Temperature Sensor: A Complete Guide

Learn the symptoms of a failing engine coolant temperature sensor in your GS450h and how to choose the best replacement part.

3 minutes to read 2007-2018 Lexus GS450h
Difficulty
4/5
Est. Time
2.5 hrs
DIY Doable?
✅ Yes
Shop Labor
$303-$444
⚠️ Drivable, but... — It is not recommended, as a faulty sensor can lead to engine overheating or an overly rich fuel mixture, potentially causing engine damage.
Key Takeaways
  • For reliable performance, choose a Denso brand aftermarket sensor, as they are the original manufacturer for Lexus.
  • Replacement is labor-intensive due to the sensor's location at the rear of the engine, making professional installation costly.
  • Common failure codes include P0117 and P0118.
  • Do not ignore symptoms like overheating, as it can lead to severe and expensive engine damage.
The Engine Coolant Temperature (ECT) sensor is a small but vital part of your Lexus GS450h's engine management system. It constantly measures the temperature of the engine's coolant. This information is sent to the main computer, the Engine Control Unit (ECU). The ECU uses this data to make critical adjustments to the fuel injection, ignition timing, and even when the transmission shifts. In a hybrid vehicle like the GS450h, proper engine temperature is essential for the performance and efficiency of both the gasoline engine and the hybrid system.

Is Your GS450h Engine Acting Up? It Could Be the Coolant Sensor.

The Engine Coolant Temperature (ECT) sensor is a common failure point on many vehicles, and the Lexus GS450h is no exception. When this sensor fails, it sends incorrect information to your car's computer, which can lead to a variety of engine performance problems. Because the sensor's data is so important for fuel mixture and cooling fan operation, ignoring a bad sensor can lead to poor fuel economy, failed emissions tests, and even engine damage.

Choosing the Right Aftermarket Sensor for Your Lexus

When it comes to electronic sensors for a Lexus, quality matters. While there are many budget-friendly options, using a low-quality sensor can cause more problems than it solves by sending inaccurate data to the engine computer.

Pro Tip: Stick with the OEM Supplier

Denso is the original equipment manufacturer (OEM) for many Toyota and Lexus parts, including this sensor. Choosing an aftermarket sensor from Denso will give you OEM quality and perfect fitment, often at a lower price than the part in a Lexus box. For a critical sensor like this, Denso is the most recommended choice by mechanics and experienced owners.

  • Tier 1 (Highly Recommended): Denso. As the OEM supplier, this is the safest and most reliable aftermarket choice.
  • Tier 2 (Reputable Aftermarket): Brands like NGK/NTK, Delphi, and Standard Ignition (SMP) are established manufacturers that generally produce reliable parts. They can be a good alternative if Denso is not available.
  • Tier 3 (Budget Options): Lesser-known or store-brand sensors are the most affordable. However, for a precision vehicle like the GS450h, there is a higher risk of inaccurate readings, which could negatively affect performance and fuel economy.

Cost to Replace the Engine Coolant Temperature Sensor

The replacement cost is heavily influenced by the sensor's difficult-to-access location. A professional mechanic may need 1.5 to 2.5 hours for the job.

Part/ServiceEstimated Cost
Shop Labor$303 - $444
New OEM Lexus Part~$135
New Aftermarket Part$13 - $83
Total Professional Replacement$438 - $579

Vehicle-Specific Issue: Fuel Pulsation Damper Recall

Some 2007-2011 Lexus GS450h models were recalled for an issue with fuel pulsation dampers, which could crack and cause a fuel leak, increasing fire risk. This is unrelated to the coolant sensor but is a critical safety issue. Check if your vehicle is affected by entering your VIN on the NHTSA website.

Frequently Asked Questions (FAQ)

Where is the coolant temperature sensor located on the GS450h?

The sensor is located on the rear of the engine, on the passenger side. It is positioned under the intake manifold and throttle body area, making it very difficult to see and reach without removing other components.

🎬 Watch a guide on accessing this hidden sensor more easily.
Can I replace the GS450h coolant sensor myself?

This is a challenging DIY job. It requires removing several brackets and hoses to gain access. Due to the tight space and complexity, it is recommended for experienced DIY mechanics only. 🎬 Watch this step-by-step GS450h sensor replacement walkthrough. A novice may find it very difficult. The estimated professional labor time is over two hours, which indicates the job's complexity.

What check engine light codes are related to a bad ECT sensor?

The most common codes are P0117 (Sensor Circuit Low Input), which means the computer sees a signal indicating extreme cold, and P0118 (Sensor Circuit High Input), indicating extreme heat. You may also see P0119 for an intermittent signal.

🎬 See how to test and replace sensors for these codes.
Do I need to drain the coolant to replace the sensor?

Yes. The sensor is threaded into a coolant passage. If you do not drain the coolant, it will spill out when the old sensor is removed. This is also a good time to replace your engine coolant if it has been a while, but be sure to use the correct type of fluid specified for your Lexus. The GS450h has separate cooling systems for the engine and the hybrid inverter; be sure you are servicing the correct one.

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Engine Coolant Temperature Sensor P0117 / P0118 | How to Test and Replace
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Engine Coolant Temperature Sensor P0117 / P0118 | How to Test and Replace
Engine Coolant Temperature Sensor P0117 / P0118 | How to Test and Replace

Technical Specifications

OEM Part Numbers: 89422-33030

The sensor is a thermistor, meaning its electrical resistance changes with temperature. It has a 2-pin female connector.

Wrenchy
Article researched & written by
Go-Parts' AI research assistant. Every article is backed by live web research, verified OEM data, and real technician knowledge — so you get accurate, up-to-date information you can trust.
Meet Wrenchy → Updated Apr 19, 2026

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.

Year Coverage
This article covers the Engine Coolant Temperature Sensor for:
  • Lexus GS450h: 200720082009201020112012201320142015201620172018
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