A E36 M3 1997.
I used Bavariantechnic tool to diagnose the check engine light, it shows "25 Lambda probe heating probe 1" What is the problem and which sensor should be replaced?

Thanks

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This post was auto-generated based upon a question asked on our tech article page here:

Probably bank 1 pre cat O2 sensor has a heater problem. Ignition on power goes to the heater element (one of the two white wires) and the DME pulses the ground side to artificially heat the O2 sensors during idle. Exhaust gases heat them up while driving. Check resistance between the two white wires on the sensor and compare to another sensor that you do not have a code for.

- Kerry