Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
11 78 610 Replacing lambda oxygen monitoring sensor (N55)
Work should only be carried out on an exhaust system that has cooled down.
Necessary preliminary tasks:
- Remove MICROFILTER HOUSING .
- Remove INTAKE SILENCER HOUSING .
- Remove rear ignition coil cover.
- Remove underbody protection. See REMOVING UNDERBODY PROTECTION (FRONT) and REMOVING REAR ENGINE UNDERCOVER .
Installation note:
The threads of new lambda monitoring sensors are already coated with Never Seez Compound.
If a lambda monitoring sensor is to be reused, apply a thin and even coating of Never Seez Compound to the thread only.
The part of the lambda monitoring sensor which projects into the exhaust system branch (sensor ceramics) must not be cleaned and not coated with lubricant.
Disconnect plug connection (1) of monitoring sensor.
Installation note:
Cable color of control sensor = black.
Cable color of monitoring sensor = grey.
Release monitoring sensor.
Tightening torque 11 78 1AZ .
Reassemble the vehicle.
Check function of Digital Engine Electronics.
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.