Skip the auto shop - Our mechanics make house calls

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

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.

A: Hello. In order to remove the oxygen sensor...

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.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: I have a 1986 Chrysler Laser turbo with 13700 miles that failed emissions. Do oxygen sensors go bad from sitting around too long?

Wow, I almost bought one of these new back in 1986. It is possible that due to age, any number of sensors can be bad, even without a Check Engine Light being set. The best way to determine that is...

Q: Fuel rail sensor faulty or fuel pressure too high

Hello there, a check engine light for too high of fuel pressure is unusual with your 2009 Audi Q5. There are one 2 possible faults going on. Either the fuel pressure is too high, or the fuel pressure sensor is...

Q: Car jumps while driving and has trouble going into gear.

If you have a manual transmission you may have an issue with your clutch. Automatic or manual transmissions can have electrical issues causing gear selection to be difficult. The jump you are referring to sounds like a hard shift. You...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.