2012 Jeep Wrangler JK Factory Service Manual 28 - DTC-Based Diagnostics

P0101-MASS AIR FLOW SENSOR PERFORMANCE

P0101-MASS AIR FLOW SENSOR PERFORMANCE

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


Theory of Operation

The Intake Air Temperature Sensor 1 is combined with the Mass Air Flow Sensor. It is located on the Air Cleaner Box and is used to monitor the temperature of the air entering the intake system. The Intake Air Temperature Sensor operates as a typical two wire sensor. It receives a 5-Volt signal on the (K362) Intake Air Temperature Sensor Signal circuit and uses the (K916) Sensor Ground circuit. When this fault code is active the EGR system will be disabled.



Possible Causes

INTAKE/EXHAUST SYSTEM PROBLEMS
HIGH RESISTANCE IN THE (K157) MASS AIR FLOW SENSOR SIGNAL CIRCUIT
HIGH RESISTANCE IN THE (K957) MASS AIR FLOW SENSOR GROUND CIRCUIT
MASS AIR FLOW SENSOR
POWERTRAIN CONTROL MODULE (PCM)

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).


1. DTC IS ACTIVE



NOTE: If any Sensor Reference DTCs are present, or if there are any other MAF Sensor DTCs present, perform the applicable diagnostic procedure before continuing with this test procedure.
1. Ignition on, engine not running.
2. With the scan tool, Clear DTCs in the PCM.
3. Start the engine and allow it to reach normal operating temperature.
4. With the scan tool, select View DTCs.


Is the status Active for this DTC?

Yes


No


2. CHECK THE INTAKE SYSTEM HOSES/TUBES



NOTE: Damaged, restricted or poorly connected intake and turbocharger related tubes will cause this DTC to set.
1. Turn the ignition off.
2. Visually inspect all air intake, crankcase vent and turbocharger related hoses/tubes and connections for leaks or restrictions.
3. Visually inspect the Charge Air Cooler hoses/tubes and connections for leaks or restrictions.


Were any problems found?

Yes


No


3. CHECK FOR HIGH RESISTANCE IN THE (K157) MASS AIR FLOW SENSOR SIGNAL CIRCUIT
1. Turn the ignition off.
2. Disconnect the Mass Air Flow Sensor harness connector.
3. Disconnect the PCM C1 harness connector.
4. Measure the resistance of the (K157) Mass Air Flow Sensor Signal circuit between the Mass Air Flow Sensor harness connector and the PCM C1 harness connector.


Is the resistance below 5.0 Ohms?

Yes


No


4. CHECK FOR HIGH RESISTANCE IN THE (K957) MASS AIR FLOW SENSOR GROUND CIRCUIT
1. Measure the resistance of the (K957) Mass Air Flow Sensor Ground circuit between the Mass Air Flow Sensor harness connector and the PCM C1 harness connector.


Is the resistance below 5.0 Ohms?

Yes


No


5. MASS AIR FLOW SENSOR

1. Connect the PCM C1 harness connector.
2. Replace the Mass Air Flow Sensor in accordance with the service information.
3. Turn the ignition on.
4. With the scan tool, Clear DTCs.
5. Start the engine and allow it to reach normal operating temperature.
6. With the scan tool, select View DTCs.


Is the status Active for this DTC?

Yes


No


6. POWERTRAIN CONTROL MODULE

1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Mass Air Flow Sensor and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals.
4. Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.
5. Look for the data to change or for the DTC to reset during the wiggle test.
6. Refer to any Technical Service Bulletins that may apply.


Were any problems found?

Yes


No