Checking Mass Air Flow Sensor

CHECKING MASS AIR FLOW SENSOR

Condition

- Diagnostic Trouble Codes (DTCs) in Motronic 4.4 absent.
- Diagnostic trouble codes (DTCs) in AW 50-42 absent.
- Engine at normal operating temperature.
- The fault is permanent.

Possible Source

- Blocked Air Cleaner (ACL) or air intake.





Checking Air Intake

- Check air intake in front of the radiator, air duct, air cleaner (ACL) housing and air cleaner insert for signs of blockage (leaves, paper etc).

Is there any blockage?

Yes:
- Remedy blockage as necessary.

No:
- Proceed to test step below.





Checking Mass Air Flow Sensor

- Ignition ON.
- Mass Air Flow (MAF) Sensor connected.
- Connect a voltmeter between mass air flow (MAF) sensor connector terminals 2 and 4.

Voltmeter should read 0.1 - 0.2 Volts.

If reading is OK:
- Proceed to Checking Ignition Cables, Distributor Cap and Rotor section.

If reading is incorrect:
- Fault-trace mass air flow (MAF) sensor.
- See: Testing By Trouble Code / Code EFI-121 and EFI-355 Mass Air Flow Sensor Signal.