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 78 530 Replacing left lambda oxygen control sensor (S65)
Special tools required:
- 11 7 030
See ENGINE - SPECIAL TOOLS .
Only perform these tasks after exhaust system has cooled down.
Necessary preliminary tasks:
- Read out fault memory in Digital Motor Electronics (DME).
- Remove transmission underbody protection.
Pull plug connection (1) from holder (2).
Disconnect plug connection (1).
Remove oxygen control sensor with special tool 11 7 030 .
If the oxygen control sensor is reused, apply a thin and even coat of Never Seez Compound to the thread only.
The part of the oxygen control sensor which projects into the exhaust system branch (sensor ceramic) must not be cleaned or come into contact with lubricant.
Secure oxygen control sensor with special tool 11 7 030 and a torque wrench (1).
Tightening torque: 11 78 1AZ . See EMISSION CONTROL .
Check function of DME.
NO RELATED
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.