Engine Controls - MIL ON And DTCs 2C84,2C85 DME Stored

SI B12 08 11
Engine Electrical Systems

October 2011
Technical Service

SUBJECT
E70 N62TU - Diagnosis of Oxygen Sensor Faults 2C84 and 2C85

MODEL
E70 X5 4.8i and X5 xDrive 4.8i produced from 10/2006 up to 3/2010

SITUATION
The Service Engine Soon lamp (MIL) is on and one or both of the following fault codes are stored in the DME:

^ 2C84 DME: Oxygen sensor behind catalytic converter, dynamic response

^ 2C85 DME: Oxygen sensor behind catalytic converter2, dynamic response

DIAGNOSIS
The most probable cause for these fault(s) being set is an exhaust leak at the exhaust flange, secured with a band clamp, located behind the catalyst close to where the post catalyst oxygen sensor is positioned.

PROCEDURE
Do not replace any parts.

Using ISTA/D 2.27 or later, follow the recommended fault test plan to check the exhaust system for leaks, check the oxygen sensor connections, and to ensure that the sensor heater circuit is working correctly.

The VACUTEC(R) Smoke Machine 625-522B-BMW (SI B11 04 07) can be very effective in helping to identify leaks prior to disassembly.

Follow the ISTA/D instructions in REP 1800020, Removing and installing the complete exhaust system (N62TU).

Once the location and cause of the leak are identified, proceed with the necessary repairs to ensure a clean tight fit.

When reinstalling the exhaust system, it is important to follow the special installation instructions using new band clamps that are properly positioned and tightened to the specified torque.

WARRANTY INFORMATION

This service information bulletin is intended to provide technical diagnostic and/or repair information only.

If a warranty claim results from the above repairs, it should be submitted following the regular warranty claim procedures.