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

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Recent Coolant Temperature Switch (Sensor) Replacement reviews

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Rating Summary
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Augustine

12 years of experience
89 reviews
Augustine
12 years of experience
Pontiac Grand Prix - Coolant Temperature Switch (Sensor) - Albuquerque, New Mexico
He arrived early for the appointment. He was friendly yet professional. He completed the repair, provided the replaced part and advised about future services needed. This was the first time I have used YourMechanic and I will more than likely used it again. I liked the convenience of the home service.
Pontiac Sunfire - Coolant Temperature Switch (Sensor) - Albuquerque, New Mexico
Augustine is very personal. My appointment was at 1pm but he didn't mind coming early. I will definitely be using this your mechanic.com and ask for him.

William

26 years of experience
65 reviews
William
26 years of experience
Chevrolet Malibu - Coolant Temperature Switch (Sensor) - Georgetown, Texas
I was very impressed with the knowledge and professionalism. William arrived promptly and started to resolve the issues with my vehicle. I would recommend William to family and friends.

Miguel

21 years of experience
154 reviews
Miguel
21 years of experience
Toyota Camry - Coolant Temperature Switch (Sensor) - East Orange, New Jersey
Mr. Miguel is an excellent mechanic and I would recommend him for any services, in fact I want him for any services on all (4) vehicles.

Collins

12 years of experience
294 reviews
Collins
12 years of experience
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.

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