What size is the socket on a 2008 Silverado oxygen sensor?

The oxygen sensor on a 2008 Silverado uses a 7/8 inch (22 mm) hex. In practice, you’ll use a dedicated oxygen sensor socket sized at 7/8 inch to remove or install the sensor, which also helps clear the sensor’s wiring.

Understanding the size and its implications

Oxygen sensors have a hex on the sensor body that the wrench or socket grabs to turn the sensor. For most GM pickups from this era, including the 2008 Silverado, that hex across flats is 7/8 inch (22 mm). Both upstream (before the catalytic converter) and downstream sensors generally use the same size, though the exact depth and clearance can vary by engine and exhaust routing. Because the sensors sit in the exhaust and their wires extend outward, a dedicated O2 socket with a cutout for the wiring is often preferred to avoid damaging the harness.

Tools you’ll typically need

To remove and reinstall the oxygen sensor safely and efficiently, you’ll want the following tools and accessories.

• Oxygen sensor socket, 7/8 inch (22 mm) – a deep socket designed to fit the sensor body and usually with a notch or hole to clear the wire.


• Ratchet with a 1/2 inch drive (or appropriate size for your socket) and a torque wrench for proper reinstallation.


• Extension bar and, if needed, a swivel or wobble joint to reach tight locations under the vehicle.


• Penetrating oil (optional) – helps loosen a rusted sensor; apply and let it soak before attempting removal.


• Torque wrench – to reinstall the sensor to the manufacturer’s torque specification (check the service manual for your engine).

Using the correct 7/8 inch socket minimizes the risk of stripping the sensor hex or damaging the wiring during removal and installation.

Safety and installation notes

Work with the exhaust cool and the engine off. Do not apply anti-seize to the O2 sensor threads, as it can affect sensor readings and performance. If you encounter a stubborn sensor, apply penetrating oil, wait, and use proper hand tools to avoid breaking the sensor or the bung.

Summary

For a 2008 Silverado, the oxygen sensor hex size is 7/8 inch (22 mm). Use a dedicated 7/8 inch O2 sensor socket (with a wire clearance notch) and appropriate hand tools to remove and install the sensors, following the vehicle’s safety procedures and torque specs in the service manual.

What size is the nut on the oxygen sensor?

The most common size for an oxygen sensor nut is 7/8 inch (22 mm) for the hexagonal part of the sensor, but some sensors also have M18 x 1.5mm internal threads or use a different nut size depending on the vehicle. To be certain, you should verify the size for your specific make and model or use an oxygen sensor socket with a 7/8-inch hex opening.
 
This video demonstrates how to use an oxygen sensor socket: 52sEast Coast ClassicsYouTube · May 22, 2020
Common sizes

• 7/8 inch (22 mm): This is the most common size for the hexagonal part of the sensor that a wrench or socket fits onto. 
• M18 x 1.5mm: This is a common thread size for oxygen sensor ports, especially for weld-in nuts or plugs. 
• Other sizes: Some older or specific models might use different sizes, so it's best to confirm with your vehicle's specifications. 

This video explains the features of an oxygen sensor socket: 58sThe Tool Connection LimitedYouTube · Jun 28, 2021
How to determine the correct size

• Measure the sensor: Use a 7/8-inch (22mm) socket to check if it fits the hex head of the sensor. 
• Check the vehicle manual: Consult your vehicle's service manual for the correct specification, especially if it's an older or less common model. 
• Look up the part number: Find the part number for your specific vehicle and cross-reference it to find the exact thread and hex size required. 

What size thread is the oxygen sensor on a Chevy Silverado?

Oxygen Sensor for 03-13 for Silverado 1500, for Sierra 1500, for Yukon - 7/8 in. Hex, M18-1.5 Thread, 4-Wire, Upstream - 16.5in Wire Length.

What size wrench do I need to replace my O2 sensor?

The most common O2 sensor wrench size is 7/8 inch (22mm). While 22mm is the standard size for most vehicles, it is always best to confirm the size for your specific car before purchasing a tool, as some specialty or older models may have different sizes, such as 27mm or 29mm.
 

• Standard size: The standard and most common size is 7/8 inch or 22mm. 
• Confirmation is key: It is a good practice to verify the size for your vehicle, as some may require a different wrench. 
• Specialized tools: A dedicated O2 sensor socket is recommended over a standard wrench, as it has a side cutout to accommodate the wires and provide clearance. 

What size socket is a GM O2 sensor?

7/8 inch
【Size】 7/8 inch (22 millimeter) hex fits almost all oxygen sensors.