Test BMW Oxygen Sensor

This bulletin applies to BMW vehicles where DTC 118602 is found (oxygen sensor before catalytic converter, fine mixture control, exhaust gas after catalytic converter too lean). This may be due to an actual engine related problem and/or DME software issues. Perform the following test plan using the latest version of ISTA.

ABL_DIT_AT1214_TVD_LV1N – Oxygen sensor before catalytic converter.

1. Electrical system troubleshooting of oxygen sensor before catalytic converter.
2. Oxygen sensor heating troubleshooting.
3. Troubleshooting function of oxygen sensor.
4. Mixture control troubleshooting.
5. Check lines and plug connections.
6. Functional check of oxygen sensor heating after repair.

It is important to complete all of the above steps in the test plan and ensure that none of the following may be a cause of the fault:

1.  Tank ventilation system.
2. Intake, exhaust and crankcase breather systems are tight and without any leaks...check with a smoke tester.
3. Injection.
4. Air mass sensor (HFM).
5. Ignition.
6. Crankshaft and camshaft sensors.
7. Throttle valve.

If no faults are stored for any of these or other components listed and the leak tests are inconclusive, replace the pre-catalyst oxygen sensor (only if not previously replaced).

Program the vehicle using ISTA/P 3.59.0 or higher.