TE. MFI #7 No Mass Air Flow (MAF) Signal

TE. MFI#7

MFI#7 No mass air flow (MAF) signal




Fault message conditions:
The fault message is logged when voltage is below 1 V.

Causes of fault:
Break or grounding in the wiring between MFI#7 and the MAF sensor.
Break or grounding in the MAF sensor.
Break to power supply terminal 5 on the MAF sensor.

Fault symptoms:
The engine runs rough. Uneven idling.

TE1




Volvo ST, Test box
- Disconnect the ST In accordance with QA2. QA. Connecting The Volvo Scan Tool (ST)
- Connect the test box to MFI and check the GND points in accordance with P1-P2. P. Test Box, Signal Description
^ Continue with Checking the MAF sensor and the wiring resistance TE2.

TE2




Checking the mass air flow (MAF) sensor and the wiring resistance
- Ignition off.
Connect an ohmmeter between MFI#7 and MFI#5 GND.
The ohmmeter should read approx. 4 ohms.

If this value is OK:
^ Check the resistance to ground (GND) TE3.

If the reading is incorrect:
^ Check the wiring between MFI#7 and the MAF sensor for breaks in accordance with NA2. NA. Checking the Wiring

TE3




Checking the resistance to GND
- Ignition off.
- Disconnect the MAF sensor.
Connect an ohmmeter between MFI#7 and MFI#5 (GND).
The ohmmeter should read infinite resistance.

If this value is OK
^ check the power supply TE4.

If the reading is incorrect
^ check the wiring between MFI#7 and the MAF sensor for grounding in accordance with NA3. NA. Checking the Wiring

TE4




Checking the power supply
- Connect the control module to the test box and the MAF sensor.
- Install the fuse.
- Ignition on.
Connect a voltmeter between terminal 5 on the MAF sensor and GND.
The voltmeter should read battery voltage.

If this value is OK:
^ Check the MAF sensor TE5.

If the reading is incorrect:
^ Check the wiring between terminal 5 and the [1][2]system relay for breaks in accordance with NA2. NA. Checking the Wiring

TE5




Checking the mass air flow (MAF) sensor
- Connect the MAF sensor.
- Start and warm up the engine.
Connect a voltmeter between MFI#7 and MFI#5 (GND).
- Take readings when the engine is unloaded and idling.
The voltmeter should read approx. 2.3 V.

If this value is OK:
Intermittent fault
^ Check the wiring between MFI#7 and the MAF sensor for loose contacts in accordance with NA5. NA. Checking the Wiring
^ Check the wiring between terminal 5 and the [1][2]system relay for loose contacts in accordance with NA5. NA. Checking the Wiring

If the reading is incorrect:
^ Try using a new MAF sensor.