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BMW E39 M5 V8 S62 Engine

How to Test the Dual Mass Air Flow Sensors

Use the following information as an aide when testing BMW E39 dual MAF sensors on V8 engines. Keep in mind, a problem with mechanical engine components can affect MAF readings and besure you have a solid base engine before condemning parts.

KOEO (Key On - Engine OFF) taken at sensor back probing with DVOM

  • B1 AFM 1.02 Volts
  • B2 AFM 1.02 Volts

Using scan tool Both AFM sensors read 0.9 Volt on GT1 under maf data stream.


Hot, engine running at idle taken at sensor back probing with DVOM

  • B1 AFM 1.30 Volts
  • B2 AFM 1.29 Volts

Using scan tool Both AFM sensors read 1.0 Volt on GT1 under maf data stream.


2500 RPM taken at sensor back probing with DVOM

  • B1 AFM 1.85 Volts
  • B2 AFM 1.75 Volts

Using scan tool Both AFM sensors read 1.5 Volt on GT1 under AFM data stream.

IAT sensor not used on bank 2 AFM. However sensors are interchangeable.

Testing using a labscope.

In Park or Neutral, parking brake ON.
Snap throttle to reach max voltage output.
(scope pattern shows a dual trace of both
AFM’s.) Green trace AFM bank 1, Yellow trace AFM bank 2.