What Size Socket Do I Need for an Oil Sending Unit?

Most oil pressure sending units use a deep 1-1/16-inch (27 mm) thin-wall socket, but sizes vary by vehicle and sensor design; other common sizes include 24 mm and 22 mm. Because of this variation, it’s best to confirm your vehicle’s specification or measure the sensor’s hex before you wrench.

Why the Socket Size Varies

“Oil sending unit” (often called an oil pressure sensor or switch) is a generic term for a family of parts that look similar but differ in hex size, body shape, and connector style. Automakers and aftermarket suppliers use different hex sizes across engines and model years, and some sensors are designed to be removed with a dedicated deep, thin-wall socket to clear the plastic electrical connector and the sensor’s body. Additionally, older tapered NPT-thread switches often use larger hexes than some modern compact sensors.

Common Socket Sizes You’ll Encounter

The list below outlines the sizes you’re most likely to need and where they commonly appear. Treat these as typical—not universal—and verify for your specific engine.

• 1-1/16 in (27 mm) deep, thin-wall: The most common size for many domestic (GM, Chrysler) and numerous Ford applications; also fits many aftermarket replacement senders.
• 24 mm deep, thin-wall: Common on many Japanese (Toyota, Honda/Acura, Nissan/Infiniti, Subaru, Mazda) and European applications, and on some late-model domestic engines.
• 22 mm: Seen on some compact Japanese sensors and switches with smaller hex flats.
• 1 in (25.4 mm) or 26 mm: Occasional use on older or certain aftermarket sensors.
• 13/16 in: Less common; found on a few small switches—be careful not to confuse it with a spark plug socket.

Because so many oil senders cluster around 27 mm and 24 mm, having both deep, thin-wall sockets on hand covers the majority of jobs; still, always verify before applying force.

How to Confirm the Correct Size Before You Wrench

To avoid rounding the hex or cracking the sensor, use the quick checks below to confirm the socket you need.

1. Check the factory service information or the parts listing for your exact year/make/model/engine; many list the required socket.
2. Measure the flats of the sensor’s hex with a caliper or an open-end wrench you know fits, then select the matching deep socket.
3. Inspect access and connector clearance; many sensors require a deep, thin-wall socket to clear the plastic connector and body.
4. If the sensor threads into an adapter or a tight recess, plan for a specialty “oil pressure sending unit” socket (usually 1-1/16 in deep, thin-wall).
5. Have both 27 mm (1-1/16 in) and 24 mm deep sockets available; one of these two fits much of the market.

These steps prevent damaged connectors, rounded hex flats, and seized sensors—saving time and parts.

Helpful Tools That Make the Job Easier

While a single socket may do, the tools below improve access, accuracy, and outcomes.

• Dedicated oil pressure sending unit socket (deep, thin-wall, typically 1-1/16 in/27 mm).
• Deep 27 mm and deep 24 mm six-point sockets (thin-wall preferred for tight wells).
• Crowfoot flare-nut wrench set (for tight spaces where a socket won’t fit).
• Torque wrench capable of low-to-moderate values appropriate for sensors.
• Sensor-safe thread sealant (PTFE paste) for tapered NPT threads if no pre-applied sealant is present; avoid tape that can shed into the oil passage.
• Dielectric grease for the electrical connector to protect against corrosion (optional).

A small, well-chosen kit prevents headaches when access is tight or the sensor sits behind intakes, brake boosters, or firewall obstacles.

Installation Notes and Cautions

Getting the size right is step one; installing correctly ensures reliability and prevents leaks.

• Remove the electrical connector gently to avoid cracking the plastic head.
• If the sensor threads into an adapter, use a backup wrench on the adapter to avoid twisting and cracking it.
• Start threading by hand to avoid cross-threading; sensors often use 1/8 NPT or 1/4 NPT tapered threads or metric straight threads with a sealing washer.
• Use sealant only where appropriate: tapered NPT threads typically require a small amount of sensor-safe paste unless the new sensor has pre-applied sealant; do not use sealant on sensors with a sealing washer unless specified.
• Tightening: follow the service manual. Over-tightening can crack the sensor or the housing; many NPT sensors are installed snug plus an additional fraction of a turn to orient and seal, while others have specific torque values.
• After installation, start the engine, inspect for leaks, and confirm oil pressure readings or that the warning lamp behaves normally.

These practices help ensure a leak-free, properly functioning sensor without damage to threads or housings.

Summary

In most cases, you’ll need a deep, thin-wall 1-1/16-inch (27 mm) socket to remove or install an oil sending unit; 24 mm and 22 mm sockets are the next most common. Verify the size for your specific engine by checking service data or measuring the hex, and use a deep, thin-wall design to clear the connector. Apply proper sealant only where specified and tighten to the manufacturer’s guidance to avoid leaks or damage.

What socket do I need for an oil drain plug?

Place a 3/8-inch (0.9 centimeters) socket in the socket wrench, fit it over the drain plug’s nut and turn it counterclockwise. The oil drain plug should open easily, draining the used oil from the engine.

What socket size do I need for an oil change?

You need a socket wrench (14mm or 15mm), an oil filter wrench, an oil drain pan, a funnel, and a new oil filter.

What tool do I need to remove an oil pressure sensor?

In general, however, you’ll need: Jack and jack stands. Oil pressure sensor socket (recommended) Ratchet and socket set.

What size socket for oil sending unit?

1 1/16 Socket
Oil Pressure Sensor Socket,1 1/16 Socket Switch Fits 3/8″ Drive or 1 1/8″ Hex Wrench,Professional Oil Pressure Switch Socket for Quick Removing/Installing Oil Sending Unit (Black)