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)
Special tools required:
Work should only be carried out on an exhaust system that has cooled down.
Necessary preliminary work:
- Remove rear ignition coil cover. See 12 REMOVING AND INSTALLING/REPLACING IGNITION COIL COVER (N55) .
- Remove rear UNDERBODY PROTECTION .
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 branch (sensor ceramics) must not be cleaned and not coated with lubricant.
Disconnect plug connection on oxygen control sensor (1).
Installation note:
Cable color of oxygen control sensor = black.
Cable color of oxygen monitoring sensor = grey.
Release oxygen control sensor (1) with special tools 11 7 030 and 11 9 150 with a suitable extension (2).
Tightening torque: 11 78 1AZ .
NO RELATED
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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.