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P0102






P0102-MASS AIR FLOW SENSOR "A" CIRCUIT LOW





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

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 Engine Control Module (ECM) 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. The engine running monitor compares an estimated fresh air flow value to the Mass Air Flow sensor reading. The ECM will light the MIL lamp immediately after this diagnostic runs and fails. The ECM will turn off the MIL lamp when the diagnostic runs and passes in four consecutive drive cycles.

- When Monitored:
When the key is on.

- Set Condition:
The frequency detected is below what is allowable for the sensor.





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

1. OTHER DTCs
1. Ignition on, engine not running.
2. With the scan tool, read DTCs.

NOTE: The Mass Air Flow Sensor, EGR Airflow Control Valve and Turbocharger Actuator get a 12V power supply from the Smart Power Relay.

Are there any EGR Airflow Control Valve, Turbocharger Actuator, or Smart Power Relay faults?

Yes

- Troubleshoot other DTCs first.

No

- Go To 2

2. (F348) SMART POWER RELAY FEED CIRCUIT AND (K916) RETURN CIRCUIT SHORTED




1. Turn the ignition off.
2. Disconnect the Mass Air Flow Sensor harness connector.
3. Turn the ignition on, engine not running.

NOTE: Check connectors - Clean/repair as necessary.

4. Measure the voltage between the (F348) smart power relay feed circuit and (K916) return circuit of the Mass Air Flow sensor harness connector.

Is voltage equal to battery voltage?

Yes

- Go To 3

No

- Go To 4

3. MAF SENSOR
1. Turn the ignition off.
2. Reconnect the disconnected Mass Air Flow sensor harness connector.
3. Ignition on, engine not running.
4. Disconnect the Mass Air Flow Sensor harness connector.
5. With the scan tool, read DTCs.

Does the DTC P0103 set?

Yes

- Replace the MAF sensor.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 4

4. (F348) SMART POWER RELAY FEED CIRCUIT AND (K916) RETURN CIRCUIT SHORTED




1. Turn the ignition off.
2. Disconnect the ECM C1 harness connector.
3. Measure the resistance between the (F348) Smart Power Relay feed circuit and (K916) Return circuit at the Mass Air Flow Sensor harness connector.

Is the resistance below 10k Ohms?

Yes

- Repair the short between the (F348) Smart Power Relay feed circuit and (K916) Return circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 5

5. (K157) SIGNAL CIRCUIT AND (K916) RETURN CIRCUIT SHORTED




1. Measure the resistance between the (K157) Mass Air Flow Sensor Signal circuit and (K916) Return circuit at the Mass Air Flow Sensor harness connector.

Is the resistance below 10k Ohms?

Yes

- Repair the short between the (K157) Mass Air Flow Sensor Signal circuit and (K916) Return circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 6

6. (K157) SIGNAL CIRCUIT OPEN




1. Measure the resistance of the (K157) Mass Air Flow Sensor Signal circuit between the Mass Air Flow Sensor harness connector and the ECM C1 harness connector.

Is the resistance below 10.0 Ohms?

Yes

- Go To 7

No

- Repair the open or high resistance in the (K157) Mass Air Flow Sensor Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

7. (K157) SIGNAL CIRCUIT SHORTED TO GROUND




1. Measure the resistance between ground and the (K157) Mass Air Flow Sensor Signal circuit at the Mass Air Flow Sensor harness connector.

Is the resistance below 10k Ohms?

Yes

- Repair the short to ground in the (K157) Mass Air Flow Sensor Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 8

8. (F348) SMART POWER RELAY FEED CIRCUIT SHORTED TO GROUND




1. Turn the ignition off.
2. Measure the resistance between ground and the (F348) Smart Power Relay feed circuit at the Smart Power Relay connector.

Is the resistance below 10k Ohms?

Yes

- Repair the short to ground in the (F348) Smart Power Relay feed circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 9

9. ENGINE CONTROL MODULE (ECM)
1. Turn the ignition off.
2. Reconnect the Mass Air Flow Sensor harness connector.
3. Turn the ignition on, engine not running.
4. Disconnect the Mass Air Flow Sensor harness connector.
5. With the scan tool, read DTCs.

Does the DTC P0103 set?

Yes

- Replace the Engine Control Module (ECM).
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Test complete, the condition or conditions that originally set this DTC are not present at this time. Using the wiring diagrams as a guide, check all related splices and connectors for signs of water intrusion, corrosion, pushed out or bent terminals, and correct pin tension.

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