Audi A6 C6: How to Replace Oxygen Sensor

A bad oxygen sensor can lead to poor gas mileage, a rough idle, and engine pinging or missing. This article will walk you through the process of replacing the oxygen sensor in your A6.

By Brett Foote - April 12, 2016

This article applies to the Audi A6 C6 (2004-2010).

Oxygen sensors play an important role in the overall function of your car's engine, but they are often overlooked when it comes to routine maintenance. Faulty oxygen sensors will often trigger a check engine light, but this isn't always the case. Once this sensor goes bad, it leads to a host of issues, including poor gas mileage, rough idle, engine misses and pinging, poor performance, and an increased amount of pollution being released into the air. If your car exhibits some or all of these symptoms, it's probably time to replace your old, worn out oxygen sensor. Keep reading and we'll walk you through the process.

Materials Needed

Flat head screwdriver
Cutting pliers
Zip ties
22mm oxygen sensor socket and extension
Ratchet

Step 1 – Replacing the bank 2 oxygen sensor

Begin by removing the air intake hose for the EVAC system by loosening the clamps with a flat head screwdriver and pulling it to the side, being careful not to damage the connector on the backside. Cut the zip ties holding the oxygen sensor to its neighboring wires. Remove the plug for sensor 2 (715) by twisting it, then disconnect it. Use a 22mm oxygen sensor socket with extension and ratchet to remove the oxygen sensor. Insert the new oxygen sensor and tighten by hand, then finish tightening with the socket and ratchet. Connect the wiring and replace the zip ties. Reinstall the air intake hose.

Figure 1. Remove the air intake hose.
Figure 2. Disconnect the wiring harness.
Figure 3. Remove and replace the oxygen sensor.

Step 2 – Replacing the bank 1 oxygen sensor

Remove the screw from the coolant overflow tank, lift it up, and set it on the fender so that it's out of the way. Cut the zip ties holding the oxygen sensor wires to the harnesses, then twist loose and disconnect the wiring harness for the sensor. Use an oxygen sensor socket or angle socket to remove the sensor. Install the new sensor and hand-tighten, then reconnect the harness. Replace the zip ties and the overflow tank.