How to Replace Upstream O2 Oxygen Sensor 04-07 Toyota Highlander L4 2 4L

Difficulty: Beginner · About 25 min · Toyota Highlander

Replace the upstream oxygen sensor on a Toyota Highlander by routing its lead away from hot parts and checking for exhaust leaks afterward.

Steps

1. Unplug and remove the old sensor

   Allow the exhaust to cool completely, unclip the sensor lead from the radiator hose, and disconnect its electrical plug. Use an oxygen sensor socket to loosen the sensor from the exhaust.

2. Install the replacement sensor

   Start the replacement sensor by hand to avoid cross-threading. Tighten it to the sensor or vehicle specification, then route the lead through its original clips.

3. Reconnect and inspect

   Reconnect the electrical plug and verify the wire cannot touch the exhaust or moving parts. Start the engine and check for leaks or warning lights.

Check your vehicle’s repair manual for exact specifications and fit.