P0102 - Mass Air Flow Sensor "A" Circuit Low
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 below a
calibrated threshold.
Default Actions:
• The MIL is illuminated.
Possible Causes
INTAKE OR EXHAUST SYSTEM LEAKING OR RESTRICTED
MAF SENSOR SIGNAL CIRCUIT OPEN
MAF SENSOR SIGNAL CIRCUIT SHORTED TO THE RETURN CIRCUIT
MAF SENSOR SIGNAL CIRCUIT SHORTED TO GROUND
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
1. Ignition on, engine not running.
2. With the scan tool, erase DTCs.
3. Start the engine and let idle for at least two minutes.
4. 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 (K188) MAF SUPPLY CIRCUIT
1. Turn the ignition off.
2. Disconnect the MAF harness connector.
3. Turn the ignition on, engine not running.
NOTE: Check connectors - Clean/repair as necessary.
4. Measure the voltage of the (K188) MAF Supply circuit at the MAF Sensor harness connector.
Is the voltage greater than 11.0 Volts?
Yes
• Go To 3
No
• Repair the (K188) Mass Air Flow Supply circuit for an open or short to ground.
• Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
3. CHECK FOR THE (K188) MAF SUPPLY CIRCUIT SHORTED TO THE (K957) RETURN CIRCUIT
1. Turn the ignition off.
2. Disconnect the PCM C1 harness connector.
3. Measure the resistance between the (K188) MAF Supply circuit and (K957) Return circuit at the MAF Sensor harness connector.
Is the resistance below 10k Ohms?
Yes
• Repair the short between the (K188) Mass Air Flow Supply circuit and (K957) Return circuit.
• Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
• Go To 4
4. CHECK FOR THE (K157) MAF SENSOR SIGNAL CIRCUIT SHORTED TO THE (K916) RETURN CIRCUIT
1. Measure the resistance between the (K157) MAF Sensor Signal circuit and (K957) Return circuit at the MAF Sensor harness connector.
Is the resistance below 10k Ohms?
Yes
• Repair the short between the (K157) MAF Sensor Signal Signal circuit and (K957) Return circuit.
• Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
• Go To 5
5. CHECK THE (K157) MAF SENSOR SIGNAL CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Measure the resistance of the (K157) MAF Sensor Signal circuit between the MAF Sensor harness connector and the PCM C1 harness connector.
Is the resistance below 5.0 Ohms?
Yes
• Go To 6
No
• Repair the (K157) MAF Sensor Signal 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).
6. CHECK THE (K157) MAF SENSOR SIGNAL CIRCUIT FOR A SHORT TO GROUND
1. Measure the resistance between ground and the (K157) MAF Sensor Signal circuit at the Mass Air Flow
Sensor harness connector.
Is the resistance below 10k Ohms?
Yes
• Repair the (K157) MAF Sensor Signal circuit for a short to ground.
• Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
• Go To 7
7. CHECK THE INTAKE SYSTEM
1. Visually inspect the Intake System for any restrictions.
2. Perform the INTAKE AIR PRESSURE TEST diagnostic procedure. (Refer to 29 - Non-DTC Diagnostics/Drivability - Diesel - Diagnosis and Testing)
Were any leaks or restrictions found?
Yes
• Repair as necessary.
• Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
• Go To 8
8. CHECK THE EXHAUST SYSTEM
1. Visually inspect the Exhaust System for any restrictions.
2. Perform the CHECKING THE EXHAUST SYSTEM FOR LEAKS diagnostic procedure. (Refer to 29 - NonDTC Diagnostics/Drivability - Diesel - Diagnosis and Testing)
Were any leaks or restrictions found?
Yes
• Repair as necessary.
• Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
• Go To 9
9. CHECK THE MASS AIR FLOW SENSOR
1. Replace the MAF Sensor in accordance with the Service Information.(Refer to 14 - Fuel System/Fuel Injection, Diesel/SENSOR, Mass Airflow (MAF) /Removal)
2. Reconnect the PCM C1 harness connector.
3. Turn the ignition on.
4. With the scan tool, erase DTCs.
5. Start the engine and allow it to idle for one minute.
6. With the scan tool, read DTCs.
Does the DTC P0102 return?
Yes
• Go To 10.
No
• Test Complete.
• Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
10. 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).