P0103 - Mass Air Flow Sensor "A" Circuit High
Theory of Operation
The Mass Air Flow (MAF) 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, which means that the resistance of it drops when the temperature drops. The drop in resistance allows more
current to flow through it in order to maintain the programmed temperature. The current flow 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. The engine running monitor compares an estimated fresh air flow value to the MAF Sensor
reading.
When Monitored and Set Conditions
When Monitored: This diagnostic runs continuously when the following conditions are met:
• With the ignition on.
Set Conditions:
• The Powertrain Control Module (PCM) has detected the Mass Air Flow (MAF) Sensor value is above a
calibrated threshold.
Default Actions:
• The MIL is illuminated.
Possible Causes
MAF SENSOR SIGNAL CIRCUIT SHORTED TO VOLTAGE
MAF SENSOR RETURN CIRCUIT OPEN/HIGH RESISTANCE
MASS AIR FLOW (MAF) SENSOR
POWERTRAIN CONTROL MODULE (PCM)
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 28 - DTCBased Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
1. ACTIVE DTC
NOTE: The MAF Sensor, EGR Cooler Bypass Valve and Turbocharger Actuator get a 12V power supply from the PCM.
1. Ignition on, engine not running.
2. Record freeze frame data and clear DTCs.
3. Turn the ignition off for one minute.
4. Turn the ignition on.
5. With the scan tool, read DTCs.
Did the DTC return?
Yes
• Go To 2
No
• Perform the INTERMITTENT CONDITION diagnostic procedure. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
2. CHECK THE (K157) MAF SENSOR SIGNAL CIRCUIT SHORT TO VOLTAGE
1. Turn the ignition off.
2. Disconnect the MAF Sensor harness connector.
3. Turn the ignition on.
4. Measure the voltage of the (K157) MAF Sensor Signal circuit in the MAF Sensor harness connector.
Is the voltage equal to battery voltage?
Yes
• Repair the short to battery in the (K157) MAF Sensor Signal circuit.
• Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
• Go To 3
3. CHECK THE (K957) MAF SENSOR RETURN CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Turn the ignition off.
2. Disconnect the PCM C1 harness connector.
3. Measure the resistance of the (K957) MAF Sensor Return circuit between the MAF Sensor harness
connector and the PCM C1 harness connector.
Is the resistance below 5.0 Ohms?
Yes
• Go To 4
No
• Repair the (K957) Mass Air Flow Sensor Return circuit for an open or high resistance.
• Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
4. CHECK THE MASS AIR FLOW SENSOR
1. Turn the ignition off.
2. Reconnect the PCM C1 harness connector.
3. Reconnect the MAF Sensor harness connector.
4. Turn the ignition on, engine not running.
5. With the scan tool, clear DTCs.
6. Disconnect the MAF Sensor harness connector and read DTCs.
Does the scan tool display DTC P0102 as active?
Yes
• Replace the Mass Air Flow Sensor in accordance with the Service Information.(Refer to 14 - Fuel System/Fuel Injection, Diesel/SENSOR, Mass Airflow (MAF) /Removal)
• Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
• Go To 5
5. POWERTRAIN CONTROL MODULE
1. Disconnect all PCM harness connectors.
2. Disconnect all related in-line harness connections (if equipped).
3. Disconnect the related component harness connectors.
4. Inspect harness connectors, component connectors, and all male and female terminals for the following conditions:
• Proper connector installation.
• Damaged connector locks.
• Corrosion.
• Other signs of water intrusion.
• Weather seal damage (if equipped).
• Bent terminals.
• Overheating due to a poor connection (terminal may be discolored due to excessive current draw).
• Terminals that have been pushed back into the connector cavity.
• Perform a terminal drag test on each connector terminal to verify proper terminal tension. Repair any conditions that are found.
5. Reconnect all PCM harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
6. Reconnect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
7. Reconnect all related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
8. With the scan tool, erase DTCs.
9. Using the recorded Freeze Frame and Environmental Data, along with the When Monitored and Set Conditions above, operate the vehicle in the conditions that set the DTC.
10. With the scan tool, read PCM DTCs.
Did the DTC return?
Yes
• Replace the Powertrain Control Module (PCM) in accordance with the Service Information. (Refer to 08 - Electrical/8E - Electronic Control Modules/MODULE, Powertrain Control/Removal) .
• Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain
Control (PCM) - Standard Procedure).
No
• Test complete.
• Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).