Hi,

2014 W212 E220 CDI.

I'm getting a "Front Left Malfunction Consult Workshop" message and the airbag light. Having read all the forums, it seems a common culprit is the seat occupancy sensor, which people solve with an emulator or new mat.

I borrowed a diagnostic tool and upon clearing the airbag ECU codes, the ones which returned were:

B275296 - the seat occupied recognition of the sensor mat "Front passenger" has a malfunction. There is an internal component fault

B00C513 - the position sensor "Front passenger seat" has a malfunction. There is an open circuit (this one appeared intermittently)

Things I have done:

• Cleared codes and the above two returned
• I have tested both batteries - the auxiliary battery is all good and reading 13.2V, the main battery is nearing end of life - 12.5V fully charged and 500/760CCA remaining capacity. On the diagnostic tool, voltage measured by the tool dropped to 11.8V with the ignition on (could this explain the intermittent code?)
• Checked all the seat connectors and cables. I see no broken wires or damaged connectors, and all are clean
• I absolutely cannot find a seat position sensor anywhere on the seat rails, on a parts diagram or online

Is this most likely to be the occupancy mat, or should I be looking elsewhere? Could the position fault be caused by the occupancy mat? Does anyone know where said seat position sensor is?

 

I have never seen this seat sensor.
We know this is seen as a LIN Module by the network.

Working with a good scanner you can further test the status of that sensor. From there decide to replace new/used part.