Thread: D2a Mass Air Flow

You'll need a copy of RAVE to check the connector id's/locations but this is the LR diagnostic for a P0102/P0103 fault. There is documentation for all the LR specific P codes available on Topix - you can buy a 1 hour subscription for the diagnostic sections for $5 or $6. A one day subscription isn't much more.

P0102
Mass air flow sensor fault Drive cycle A:Signal out of range - below minimum.

Possible Causes:
1. MAFS contaminated.
2. Open circuit - C636/23 (UG) to C149/5 (UG).
3. Open circuit - C636/9 (RB) to C149/3 (RB).
4. 5V MAFS supply voltage C149/4 (R) to C149/3 (RB).
5. 12V MAFS supply voltage C149/2 (NK) to C149/3 (RB).
6. Connectors C149, ECM C636 (B).
7. Fuse F2 Engine Compartment Fusebox.
8. MAFS faulty.

1. MAFS contaminated.
CHECK THE FOLLOWING:
Visually inspect the metal and plastic mesh on the upstream side of the airflow meter.
If this mesh is contaminated then this is a good indication that the sensor film is also contaminated.
POSSIBLE FAULTS
MAFS Fault - Contaminated hot film sensor.

2. Open circuit - C636/23 (UG) to C149/5 (UG).
OPEN_CIRCUIT
Check resistance > 1Mohm

3. Open circuit - C636/9 (RB) to C149/3 (RB).

OPEN_CIRCUIT
Check resistance > 1Mohm

4. 5V MAFS supply voltage C149/4 (R) to C149/3 (RB).
CHECK THE FOLLOWING:
5V MAFS supply voltage C149/4 (R) to C149/3 (RB)..
ACCEPTABLE RESULTS Between 4.5V and 5.5V.
DIAGNOSTIC HINTS
If the voltage is too high a short circuit to battery or faulty ECM should be suspected. If the voltage is too low an open circuit or connector problem should be suspected.

5. 12V MAFS supply voltage C149/2 (NK) to C149/3 (RB).
CHECK THE FOLLOWING:
12V MAFS supply voltage C149/2 (NK) to C149/3 (RB)..
ACCEPTABLE RESULTS Between 11.5V and 15.0V.
DIAGNOSTIC HINTS
If the voltage is not present check F2 Engine Compartment Fusebox and open circuit C149/2 (NK) to C570/5 (NK).

6. Connectors C149, ECM C636 (B).

7. Fuse F2 Engine Compartment Fusebox.
POWER_DISTRIBUTION
Check for fuse not correctly inserted, fuse blown, fuse connections loose, damaged or corroded.
CONNECTOR
Check for connector not correctly latched, backed out pins, damaged pins, corroded pins

8. MAFS faulty.
Certain diagnostics may also perform further checks to try and narrow down the fault. Eg Check if other circuits fed by the same fuse are also experiencing problems
CHECK THE FOLLOWING:
Check MAFS by substituting with known good unit.

Good news! New MAF got delivered today. Coupla minutes installing it and the Disco runs beautifully! No more hesitations at intersections, more low rev power and more pull up hills.
OBD scan tool has no fault codes anymore and oddly now seems to pick up more readings i.e engine power and torque, that it never picked up before...
MAF cost me around $160 delivered from the States, not bad I reckon...woulda been better if I didnt already spend $50 on a dodgey second hand one!

PM sent
cheers
Paul