What size socket is a coolant temperature sensor?
There is no universal socket size for coolant temperature sensors; hex head measurements vary by make and model. The most common sizes you’ll encounter are 19 mm (about 3/4 inch) and 22 mm (about 7/8 inch), but some sensors use 17 mm, 18 mm, or other sizes. Always verify with your vehicle’s service manual or by measuring the sensor directly.
In practice, identifying the correct size means checking the exact sensor fitted to your car, since the socket you need is determined by the sensor’s hex head, not by the thread pitch or overall location. This article outlines typical sizes you might see and how to determine the right one for your vehicle.
Common hex sizes you may encounter
Below are the hex head sizes you’re most likely to encounter on coolant temperature sensors. Knowing these sizes helps you pick the right socket or wrench when replacing or servicing the sensor.
- 17 mm (approximately 11/16 inch)
- 18 mm (approximately 23/32 inch)
- 19 mm (approximately 3/4 inch)
- 22 mm (approximately 7/8 inch)
Sizes outside this range are possible on some European, Asian, or high-performance applications. If none of these fit, measure the sensor’s hex head directly or consult the service manual for your exact model.
How to identify the exact size for your vehicle
To determine the precise socket or wrench size for your car’s coolant temperature sensor, follow these steps.
- Check the vehicle’s service manual or official repair guides for the exact CTS replacement specs, including the hex head size.
- Inspect the sensor in place and measure its hex across flats with a caliper or a set of calipers or compare it to a known-size wrench or socket.
- If you still can’t identify it, remove the sensor carefully and bring the hex head to an auto parts store or use an adjustable torque wrench set to the approximate size to test fitment.
- Verify the thread size and sensor type (some sensors have different thread pitches or special spacers); use the correct replacement to avoid leaks or sensor damage.
- Reinstall with manufacturer-recommended torque and, if advised, apply the appropriate thread lubricant or anti-seize product as directed by the sensor’s manufacturer.
By confirming the hex head size and the sensor’s thread specifications, you’ll avoid cross-threading and damaged cooling system components during removal or installation.
Summary
The socket size for a coolant temperature sensor is model-dependent. While 19 mm and 22 mm are the most common hex sizes, you may encounter 17 mm, 18 mm, or other dimensions. Always verify with the service manual or measure the sensor directly, and follow proper removal and installation procedures to ensure a proper seal and accurate readings.
