How to Replace a Cylinder Head Coolant Temperature Sensor

The coolant temperature sensor in your vehicle’s cylinder head plays a key role in the engine’s operation. It sends a signal to the electronic control unit (ECU) that provides information on the coolant temperature and supplies a signal to the temperature gauge in the dashboard.

Coolant temperature sensor failures are usually accompanied by engine running issues such as sluggish acceleration, hard starting when hot or cold, and the Check Engine or Service Engine Soon Light coming on in possible overheating conditions. If the Check Engine Light is on, diagnosis is usually straightforward by connecting a scan tool to the onboard diagnostic port and reading the fault code.

Part 1 of 1: Replacing the temperature sensor

Materials Needed

Step 1: Be sure the engine is cool. Locate the main pressure cap for the cooling system and open it enough to relieve any pressure in the cooling system, then reinstall the cap so it seals properly.

Step 2. Locate the coolant temperature sensor. Many engines have multiple sensors that look similar to each other, so an investment in either a paper version or an online subscription for your vehicle’s repair manual will pay dividends in a generally faster repair and reduce guesswork by guiding you to the exact part and location.

ALLDATA is a good online source that has most manufacturer’s repair manuals.

See the connector images below. The tab to lift to release the connector is at the top, toward the back of the connector on the left, the nub that it engages is at the top front of the one on the right.

cylinder head temperature sensor, both ends of connector

Step 3. Disconnect the electrical connector. The connector may plug into the sensor itself, or there may be “pigtail” wires leading from the sensor with the connector on the end of the wires. These connectors have a locking tab so that the connection remains secure. Using the pocket screwdriver (if needed), pry up the tab enough to clear the locking nub on the mating side, then separate the connection.

  • Tip: If you’re working on an older vehicle, be aware that the plastic on the connector may have become brittle from heat and the tab may break off, so use just enough pressure to raise the tab enough to release the connector.

removing the coolant temp sensor

Step 4. Unscrew the temperature sensor with an appropriately sized wrench or socket. Be aware that there may be coolant loss from the opening of the cylinder head when the sensor is removed, so be ready to screw in the new sensor to try to keep this at a minimum.

If equipped, use a new seal, usually a copper or aluminum washer, with the new sensor.

Step 5. Snug down the new sensor. Use the wrench and tighten just enough to ensure a good seal to the cylinder head.

  • Warning: Do not use excessive force when tightening the sensor! Too much pressure can result in a broken sensor which can be difficult to remove, or the threads in the cylinder head being stripped, which may require a new cylinder head, a very expensive repair.

Step 6. Reconnect the wiring. Make sure the wires are clear and will remain clear of any moving parts like the engine drive belt or pulleys, or any high heat items like an exhaust manifold.

Step 7. Verify that the engine coolant is at the correct level. Clear any OBD fault codes with the scan tool that haven’t corrected themselves now that there’s a proper signal from the temperature sensor.

Get a quote for a service: If you’re not quite comfortable diagnosing and changing your own coolant temperature sensor, a professional mechanic, such as from YourMechanic, will be happy to do it for you at your home or office.


Next Step

Schedule Coolant Temperature Switch (Sensor) Replacement

The most popular service booked by readers of this article is Coolant Temperature Switch (Sensor) Replacement. YourMechanic’s technicians bring the dealership to you by performing this job at your home or office 7-days a week between 7AM-9PM. We currently cover over 2,000 cities and have 100k+ 5-star reviews... LEARN MORE

SEE PRICING & SCHEDULING

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Recent Coolant Temperature Switch (Sensor) Replacement reviews

Excellent Rating

(305)

Rating Summary
281
9
0
4
11
281
9
0
4
11

Collins

12 years of experience
488 reviews
Collins
12 years of experience
GMC Acadia V6-3.6L - Coolant Temperature Switch (Sensor) - Atlanta, Georgia
Collins was very professional, knowledgeable, and on time. He has a great personality and helped me understand what was going on with my car. I highly recommend Collins.
Buick LeSabre - Coolant Temperature Switch (Sensor) - Atlanta, Georgia
Collins was very knowledgeable about the service and patient with my questions He also found other problems and explained so that I could understand. I will use him for these fixes too. Clean, professional personality. He was also on-time showing up a little early which was good for my anxiety when its starts getting close to appointment time. Today is only day one after my service and I took one small trip later on late afternoon and it was a good trip.

Marco

29 years of experience
221 reviews
Marco
29 years of experience
Subaru Outback H4-2.5L - Coolant Temperature Switch (Sensor) - Perris, California
Excellent mechanic!!! Marco provided a expert professional service on my vehicle today; thank you kindly.
Land Rover Range Rover Sport - Coolant Temperature Switch (Sensor) - Upland, California
Marco came to my house trice - he called 30 minutes before - he was very knowledge and pleasant - and he fixed the problem very fast. His service was outstanding - the best mecanic I have ever had - I am very pleased and I will GREATLT recommend his services

Mathew

6 years of experience
54 reviews
Mathew
6 years of experience
Dodge Charger V6-3.6L - Coolant Temperature Switch (Sensor) - Philadelphia, Pennsylvania
Very friendly and professional, came early to work and walked me through what was completed and even given advise on preventative steps in the future. Would definitely recommend!

Diana

18 years of experience
90 reviews
Diana
18 years of experience
Volkswagen Tiguan L4-2.0L Turbo - Coolant Temperature Switch (Sensor) - Summit, New Jersey
Diana was very thorough and explained what she did, what she found and provided helpful insights. Came across as very knowledgable and trustworthy.

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

Related articles

How to Replace a Fuel Rail Sensor
The fuel system has a fuel rail sensor which fails when the engine operates erratically, has difficulty starting, or the Check Engine Light comes on.
How to Replace a Steering Angle Sensor
A steering angle sensor fails if the Traction Control Light illuminates, the steering wheel feels loose, or the vehicle drives differently.
P0337 OBD-II Trouble Code: Crankshaft Position Sensor A Circuit Low Input
P0337 means that the crankshaft is suffering because of low voltage. This could be due to sensor not being aligned properly or electrical problems.

Related questions

Amount of A/C refrigerant required for my Hyundai Santa fe 2002 GLS
It should have a sticker under the hood stating the amount of R134a to be 1.35lbs or .6kg. You should put about 1 oz of A/C oil in the condenser and the compressor should have the amount it needs on...
What could be cause of coolant leak after replacing cap and low fan relay? 2012 Chevrolet Cruze
Coolant leaks (https://www.yourmechanic.com/services/coolant-is-leaking-inspection) can originate from a few different places. A pressure check of the cooling system can be performed, subjecting the entire system to higher-than-normal pressures under controlled circumstances to find weak points. Leaks could be coming from hoses,...
Engine gets hotter sitting in traffic - 2007 Chevrolet Malibu
Hi there. This could be normal operation, but the cooling fans could be starting to have issues. Perform a visual inspection of the cooling fans to make sure when they come on that they operate properly; they should move a...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com