P252A: The DME loses communication with the oil-condition sensor

The N63 chart maps P252A to BMW 1C5104: communication with the oil-condition sensor has been lost. Although the generic title refers to an oil-quality sensor circuit, this implementation specifically monitors the information link between the sensor and DME.

Communication loss has a delay

BMW identifies an open BSD connection between the two components and a defective oil-condition sensor as possible sources. The monitoring conditions include Terminal 15 and electrical-system voltage above 9.14 V. The interruption must remain present for more than 120 seconds before it is stored.

That two-minute delay matters when evaluating a short workshop test. Restoring a displayed reading momentarily or checking the system for only a few seconds does not demonstrate that communication remains reliable for the monitored interval.

Separate missing information from oil condition

The chart lists unavailable oil-level measurement in the instrument cluster as a possible effect. A missing display is consistent with missing sensor communication, but it does not prove that the oil is low, overfilled, or degraded. Those are separate questions requiring the correct vehicle procedures.

BMW's service sequence checks the BSD connection and then considers sensor replacement. A fluid change alone does not address an interrupted communication line. Conversely, the code is insufficient evidence to replace the DME or every device using the same network.

Verification should establish reliable sensor communication and the return of the relevant measurement function over sufficient operating time. The chart supplies no connector pin assignments or electrical-network test values, so those must be obtained from the exact vehicle wiring information.

Source and applicability

BMW diagnostic chart, P252A. 2011 BMW X6 xDrive50i (E71), N63 4.4L turbo; BMW DME monitor chart reproduced by Operation CHARM. These values describe that documented monitor; they are not universal specifications for every vehicle displaying this code.