P0101

P0101-MASS AIR FLOW SENSOR "A" CIRCUIT PERFORMANCE





For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

The Mass Air Flow Sensor is a frequency based device. A constant voltage is applied to a heated wire. This wire is positioned in the air stream and is heated by the electrical current that the voltage produces. As air flows across it, it cools down. The heated wire or film is a positive temperature coefficient (PTC) resistor. This means that it's resistance drops when it's temperature drops. The drop in resistance allows more current to flow through it in order to maintain the programmed temperature. This current is changed to a frequency which is sent to the Powertrain Control Module (PCM) and interpreted as air flow. Adjustments for air temperature and humidity are taken into consideration since they also affect the temperature of the heated wire or film. This monitor fails if the MAF correction factor is beyond it's calibrated range. The PCM will turn on the MIL lamp immediately after this monitor runs and fails. The PCM will turn off the MIL lamp when the diagnostic runs and passes in four consecutive drive cycles.

- When Monitored:
Engine running with engine speed above 1050 RPMs and below 2150 RPMs, vehicle speed greater than 3.1 MPH, and coolant temperature above 179.6°F (82°C).

- Set Condition:
The Mass Air Flow correction factor (calculation based on expected O2 in exhaust versus actual O2 Sensor measurement) is beyond the calibrated range (lower than minimum threshold or higher than maximum threshold).





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. ACTIVE DTC

NOTE: This fault can potentially be set by an aftermarket Air Filter Box and/or filter. Non factory filter assemblies are not calibrated to the factory PCM thresholds or settings. If the vehicle has a modified filter assembly and this fault is set, notify the customer that the vehicle needs to be returned back to the stock assembly in order to properly repair the vehicle.

NOTE: If there are any other EGR, Turbocharger, or Intake system DTCs present, repair those DTCs before proceeding.

1. Turn the ignition on.
2. With the scan tool, record all Freeze frame data.
3. With the scan tool, erase DTCs.
4. Turn the ignition off for 75 seconds.
5. Start the engine attempt to duplicate the conditions that set the DTC.
6. With the scan tool, read DTCs.

Did the DTC return?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION - 6/7L diagnostic procedure. Intermittent Condition Test

2. CHECK THE MAF SENSOR
1. Start the engine. Warm the engine up to operating temperature and then let it idle for five minutes.

NOTE: This is how long it takes for the EGR Valve to close.

2. With the scan tool in Data Display, verify that the EGR Valve is at 0%.
3. With the scan tool, read the MAF Sensor value.

Does the Mass Air Flow Sensor read from 1.36 - 3.07 kg/min for an auto transmission, or 1.58 - 3.41 kg/min for a manual transmission?

Yes

- Go To 3

No

- Replace the Mass Air Flow Sensor.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

3. CHECK THE AIR FILTER
1. Remove lid from air filter box.
2. Remove air filter and inspect for excessive debris or filter media damage.
3. Make sure the filter was installed properly.

Is the air filter damaged or full of debris (restricted)?

Yes

- Replace the Air Filter.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 4

4. CHECK THE MAF SENSOR
1. Turn the Ignition off.
2. Remove MAF sensor from the air filter box.

Is it free from debris?

Yes

- Go To 5

No

- Clean the Mass Air Flow Sensor using low pressure air and reinstall, repair complete.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

5. CHECK FOR AN AIR LEAK IN THE INTAKE SYSTEM
1. Perform the INTAKE AIR SYSTEM PRESSURE TEST diagnostic procedure. Intake Air System Pressure Test
2. Any leak between the air box to the intake manifold could cause this fault.

Were there any Intake Air System leaks?

Yes

- Repair the leak in the Intake Air System.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Replace the Mass Air Flow Sensor.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.