P0101-MAF SENSOR SIGNAL NEGATIVE DEVIATION

For a complete wiring diagram Refer to Section 8W

When Monitored:
Engine temperature between 59.9°C and 99.9°C. Intake Air Temperature reading is steady. Atmospheric pressure below 1500 hpa. Boost pressure is between 750 hpa and 2400 hpa.
Set Condition:
The MAF Sensor reading is below the calibrated map value for more than 2.0 seconds.

Possible Causes

AIR FILTER

AIR RESTRICTION

CHECKING FOR AIR LEAKS

EGR VALVE

MASS AIRFLOW SENSOR

INTERMITTENT CONDITION

Diagnostic Test

1. VERIFY ACTIVE DTC

NOTE: If DTC P0641, P0651 or P0697 is present with this DTC, diagnose DTCs P0641, P0651 or P0697 before diagnosing this DTC.

NOTE: Inspect all air intake and turbocharger related tubes for damage, restriction or poor connection. Any of these conditions can cause a this DTC to set.

NOTE: If the ECM detects and stores a DTC, the ECM also stores the engine/vehicle operating conditions under which the DTC was set. Some of these conditions are displayed on the scan tool at the same time the DTC is displayed.

NOTE: Before erasing stored DTCs, record these conditions. Attempting to duplicate these conditions may assist when checking for an active DTC.

Turn the ignition on.
With the scan tool, erase the ECM DTCs.
Test drive the vehicle.
With the scan tool, read the ECM DTCs.

Does the scan tool display a Mass Air Flow Sensor DTC?

Yes

Go To 2

Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)

2. AIR FILTER

Turn the ignition off.
Remove and inspect the Air Filter for soiling or excessive dirt and debris which may cause air flow restriction.

Were any of these problems found?

Yes

Replace the Air Filter element.

Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

Go To3

3. AIR RESTRICTION

NOTE: Inspect all air intake, crankcase vent and turbocharger related tubes for damage, restriction or poor connection. Any of these conditions can cause a this DTC to set.

NOTE: Inspect the exhaust system and related tubes for damage, restriction or poor connection. Any of these conditions can cause a this DTC to set.

Inspect the intake system, exhaust system and related tubes and connections.

Were any problems found?

Yes

Repair or replace as necessary.

Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

Go To4

4. CHECKING FOR AIR LEAKS

Remove the Inlet Pressure Sensor.
Connect smoke machine 84-04 to the Inlet Pressure Sensor port in the intake duct and begin injecting smoke into the intake system.
Observe all intake system components for evidence of smoke leakage.

Is there evidence of smoke leakage?

Yes

Repair or replace as necessary.

Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

Go To5

5. EGR VALVE

NOTE: An EGR Valve that is stuck partially open can cause this DTC to set. Hard starting, rough running and black smoke from the tailpipe are signs of an EGR Valve that is stuck open.

While starting and test driving the vehicle, observe for the conditions mentioned in the note above.

Does the vehicle exhibit these conditions?

Yes

Replace the EGR Valve.

Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

Replace the MAF Sensor.
Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).