How to Install an Oxygen Sensor Bung Plug Correctly

Quick Answer

Installing an oxygen sensor bung plug correctly requires cleaning the threads, applying anti-seize, hand-threading to avoid cross-threading, and torquing to a moderate spec—typically 20-30 ft-lbs for stainless steel plugs.

Step-by-Step Installation Guide

1. 1. Prepare the Bung and Plug: Clean the bung threads inside the exhaust pipe using a wire brush or thread chaser to remove carbon buildup or debris. Wipe the plug threads clean with a lint-free cloth. Apply a thin, even layer of anti-seize compound to the plug threads—do not over-apply, as excess can contaminate the exhaust stream. Skipping thread cleaning can cause cross-threading or a poor seal.
2. 2. Hand-Thread the Plug: Insert the plug into the bung and turn it by hand clockwise until it seats snugly. Use only finger pressure—never force it. If resistance is felt before the plug is fully seated, back it out and re-check alignment. Using a wrench too early risks cross-threading, which ruins both the plug and the bung.
3. 3. Torque to Specification: Tighten the plug with a torque wrench set to 20-30 ft-lbs (27-41 Nm) for stainless steel plugs. The hex flange design of the MagnaFlow plug allows a socket to fit securely. Do not exceed 30 ft-lbs, as overtightening can strip threads or crack the bung weld. Over-torquing is the most common mistake; use a torque wrench, not an impact gun.
4. 4. Check for Leaks: Start the engine and let it idle. Listen for hissing sounds around the bung area. Use a soapy water spray bottle to check for bubbles at the plug-bung interface. If bubbles appear, tighten the plug slightly (no more than 5 ft-lbs) and recheck. A small leak can be fixed by re-torquing, but if the plug is damaged, replace it.

Recommended Product

• MagnaFlow (20 Pack) Hex Flanged Performance Exhaust Oxygen Sensor Plugs 10044: MagnaFlow's Hex Flanged Performance Exhaust Oxygen Sensor Plug 10044 is built from high-quality stainless steel for maximum durability and corrosion resistance, with a thread diameter of 18 x 1.5. The stainless steel construction resists rust and seizing in exhaust heat cycles, and the hex flange provides a secure surface for torquing without stripping.