Q: How do you get access to replace the O2 sensors on a Audi A6 4.2 engine? There does not appear to be any room?

asked by on October 31, 2016

The front O2 Sensors are difficult to extract and replace on a 4.2 L engine. The termination plug is easy to remove. Access to the muffler to extract the O2 sensor appears impossible. Clearly it is not possible from below, ie not possible from below the car.

My car has 100000 miles.
My car has an automatic transmission.

Hello. In order to remove the oxygen sensors, you will likely need an offset oxygen sensor wrench. An offset oxygen sensor wrench will be compact enough to fit into low clearances but still provide enough torque to break the sensors loose. Once the sensors are loosened, you can unscrew them by hand.

Reinstalling the new sensors would be a simple reverse of the removal procedure, start them by hand and then torque them down with the wrench. This procedure is usually done form above, through the engine bay, and may require the removal of some engine components, such as intake tubes or the coolant reservoir to properly access. If you cannot access the sensors even with an oxygen sensor wrench then another option would be to undo the manifolds in order to provide clearance to reach the sensors.

If you need help having this done, a certified technician from YourMechanic can come to your car’s location to replace the oxygen sensors for you.

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