Engine Control System (4HK1) 1A-99
DTC P0102 or P0103 (Flash Code 91)
Circuit Description
The mass air flow (MAF) sensor is an air flow meter
that measures the amount of air that enters the engine.
It is fitted between the air cleaner and turbocharger. A
small quantity of air that enters the engine indicates
deceleration or idle speed. A large quantity of air that
enters the engine indicates acceleration or a high load
condition. The sensor has the following circuits.
• 12 volts reference circuit
• Low reference circuit
• MAF sensor signal circuit
The ECM monitors the MAF sensor signal voltage. This
output voltage will display on the scan tool as a voltage
parameter and as a grams per cylinder (g/cyl)
parameter. If the ECM detects an excessively low or
high signal voltage, DTC P0102 or P0103 will set.
Condition for Running the DTC
• DTCs P0560 and P060B are not set.
• The battery voltage is between 18 to 32 volts.
• The ignition switch is ON.
• The engine is running.
• The engine speed is less than 1500RPM. (DTC
P0102)
Condition for Setting the DTC
• The ECM detects that the MAF sensor signal
voltage is less than 0.1 volts for 3 seconds. (DTC
P0102)
• The ECM detects that the MAF sensor signal
voltage is more than 4.9 volts for 3 seconds. (DTC
P0103)
Action Taken When the DTC Sets
• The ECM illuminates the MIL when the diagnostic
runs and fails. Refer to DTC Type Definitions for
Action Taken When the DTC Sets - Type A.
• The ECM uses a MAF substitution of default value.
• The ECM limits fuel injection quantity.
• The ECM inhibits EGR control.
Condition for Clearing the DTC
• Refer to DTC Type Definitions for Condition for
Clearing the MIL/ DTC - Type A.
Diagnostic Aids
• If an intermittent condition is suspected, refer to
Intermittent Conditions in this section.
Schematic Reference:
Engine Controls Schematics
Connector End View Reference:
Engine Controls
Connector End Views or ECM Connector End Views
Circuit/ System Testing DTC P0102
Step
Action
Value(s)
Yes
No
1
Did you perform the Diagnostic System Check
- Engine Controls?
—
Go to Step 2
Go to Diagnostic
System Check -
Engine Controls
2
1.
Install a scan tool.
2.
Turn OFF the ignition for 30 seconds.
3.
Start the engine.
4.
Monitor the DTC Information with a scan tool.
Is DTC P0560 also set?
—
Go to DTC P0560
Go to Step 3
3
Observe the Mass Air Flow (MAF) Sensor
parameter with a scan tool.
Is the MAF Sensor parameter less than the
specified value?
0.1 volts
Go to Step 4
Go to Diagnostic
Aids
4
1.
Turn OFF the ignition.
2.
Disconnect the MAF sensor harness
connector.
3.
Connect a test lamp between the 12 volts
reference circuit (pin 1 of J-38) and a known
good ground.
4.
Turn ON the ignition, with the engine OFF.
Does the test lamp illuminate?
—
Go to Step 5
Go to Step 6
LG4HKED-WE-0871.book 99
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