The mass air flow (MAF) sensor is an air flow meter that measures the amount of air entering the engine. The PCM uses the MAF sensor frequency signal in order to provide the correct fuel delivery for a wide range of engine speeds and loads. A small quantity of air entering the engine indicates deceleration or idle. A large quantity of air entering the engine indicates an acceleration or high load situation. The MAF sensor has an ignition 1 voltage circuit, a ground circuit and a signal circuit. The PCM applies a voltage to the sensor on the signal circuit. The sensor uses the voltage in order to produce a frequency based on inlet air flow through the sensor bore. The PCM uses the barometric pressure at key ON, and the engine RPM in order to calculate a predicted MAF value. The PCM compares the actual MAF sensor frequency signal to the predicted MAF value in order to determine if the signal is stuck based on a lack of variation, or is too low or too high for a given operating condition. DTC P0101 will set if the actual MAF sensor frequency signal is not within a predetermined range of the calculated MAF value.
• | DTCs P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0121, P0122, P0123, P0335, P0336, P0401, P0440, P0442, P0443, P0446, P0449, P1106, P1107, P1111, P1112, P1121, P1122, P1441 are not set. |
• | The engine is running. |
• | The ignition 1 signal is between 11 volts and 18 volts. |
• | The TP sensor angle is steady within a range of 5 percent or less. |
• | The TP sensor angle is less than 95 percent. |
• | The MAP sensor is less than 80 kPa. |
• | All of the above conditions are present for at least 2 seconds. |
• | The actual MAF sensor frequency signal is not within a predetermined range of the calculated MAF value. |
• | The above condition is present for 8 seconds. |
• | The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic has been run and failed. |
• | The PCM will store the conditions which were present when the DTC set as Freeze Frame/Failure Records data. |
• | The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been run and passed. |
• | The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. |
• | Use the scan tool in order to clear the DTCs. |
Inspect for the following conditions:
• | A misrouted harness. Inspect the harness of the MAF sensor in order to verify that it is not routed too close to the following components: |
• | The secondary ignition wires or coils |
• | Any solenoids |
• | Any relays |
• | Any motors |
• | Any unmetered air that enters the engine may cause this DTC to set. Verify that the oil dipstick is fully seated and the oil filler cap is secure. |
• | Inspect for any vacuum leaks downstream of the MAF sensor. |
• | A wide open throttle acceleration should cause the MAF display to increase from 4-7 g/s at idle to 150 g/s or more during the 1-2 shift. If the change in the display is not observed, inspect for a restriction. |
• | The barometric pressure that is used in order to calculate the predicted mass air flow value is based on the MAP sensor at key ON. A skewed MAP sensor will cause the calculated mass air flow value to be inaccurate. The value shown for the MAP sensor display will vary with the altitude. With the ignition ON and the engine OFF, 103 kPa is the approximate value at or near sea level. The value decreases by approximately 3 kPa for every 1,000 feet of altitude. |
If you suspect the vehicle condition may be related to aftermarket accessories, refer to Checking Aftermarket Accessories in Wiring Systems.
If the condition is intermittent, refer to Intermittent Conditions .
The numbers below refer to the step numbers on the diagnostic table.
Any unmetered air that enters the engine may cause this DTC to set. This step eliminates the conditions which can cause a DTC to set with a normally operating MAF sensor.
This step verifies the signal circuit from the MAF sensor electrical connector to the PCM. A voltage reading of less than 4 volts or greater than 6 volts indicates a malfunction in the wiring or a poor connection.
Step | Action | Values | Yes | No | ||||||||||||||||||||||||||
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Schematic Reference: Engine Controls Schematics | ||||||||||||||||||||||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls ? | -- | Go to Step 2 | |||||||||||||||||||||||||||
2 |
Does the scan tool display any other DTCs set? | -- | Go to Step 3 | |||||||||||||||||||||||||||
3 |
Does the DTC fail this ignition? | -- | Go to Step 4 | Go to Diagnostic Aids | ||||||||||||||||||||||||||
4 |
Does the scan tool indicate that the MAP sensor voltage is within the specified range? | 0.8-4 V | Go to Step 5 | Go to DTC P0106 | ||||||||||||||||||||||||||
Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 6 | |||||||||||||||||||||||||||
6 |
Does the scan tool indicate that the MAP sensor value changed smoothly through the entire range of the test? | -- | Go to Step 7 | Go to DTC P0106 | ||||||||||||||||||||||||||
7 | Apply 20 inches Hg vacuum to the MAP sensor. Does the scan tool indicate that the MAP sensor value is equal to or less than the specified value? | 34 kPa | Go to Step 8 | Go to DTC P0106 | ||||||||||||||||||||||||||
8 | Disconnect the vacuum source from the MAP sensor. Does the scan tool indicate that the MAP sensor value returned to the original value that was observed in step 6? | -- | Go to Step 9 | Go to DTC P0106 | ||||||||||||||||||||||||||
9 | Use a scan tool in order to observe the TP sensor angle parameter from closed throttle to wide open throttle. Does the scan tool indicate that the TP sensor value changed smoothly and completely through the specified range of the test? | 0-100% | Go to Step 10 | Go to DTC P0121 | ||||||||||||||||||||||||||
Does the voltage measure near the specified value? | 5 V | Go to Step 11 | Go to Step 12 | |||||||||||||||||||||||||||
11 | Connect a test lamp between the ignition 1 voltage circuit of the MAF sensor and the ground circuit of the MAF sensor. Refer to Circuit Testing in Wiring Systems. Does the test lamp illuminate? | -- | Go to Step 19 | Go to Step 14 | ||||||||||||||||||||||||||
12 | Does the voltage measure less than the specified value? | 4.5 V | Go to Step 15 | Go to Step 13 | ||||||||||||||||||||||||||
13 |
Important:: Disconnecting the PCM connectors may eliminate the short to voltage if the signal circuit is shorted to another PCM circuit.
Does the voltage measure at the specified value? | 0 V | Go to Step 22 | Go to Step 18 | ||||||||||||||||||||||||||
14 | Connect a test lamp between the ignition 1 voltage circuit of the MAF sensor and a good ground. Refer toCircuit Testing in Wiring Systems. Does the test lamp illuminate? | -- | Go to Step 16 | Go to Step 17 | ||||||||||||||||||||||||||
15 |
Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 20 | ||||||||||||||||||||||||||
16 | Repair the high resistance or an open in the ground circuit of the MAF sensor. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 23 | -- | ||||||||||||||||||||||||||
17 |
Important: The ignition 1 voltage circuit of the MAF sensor is spliced to other components on the vehicle.
Did you complete the repair? | -- | Go to Step 23 | Go to Step 21 | ||||||||||||||||||||||||||
18 | Repair the short to voltage in the signal circuit of the MAF sensor. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 23 | -- | ||||||||||||||||||||||||||
19 | Inspect for poor connections at the harness connector of the MAF sensor. Refer to Intermittent and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 21 | ||||||||||||||||||||||||||
20 | Inspect for poor connections at the harness connector of the PCM. Refer to Intermittent and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 22 | ||||||||||||||||||||||||||
21 | Replace the MAF sensor. Refer to Mass Airflow Sensor Replacement . Did you complete the replacement? | -- | Go to Step 23 | -- | ||||||||||||||||||||||||||
22 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 23 | -- | ||||||||||||||||||||||||||
23 |
Does the DTC run and pass? | -- | Go to Step 24 | Go to Step 2 | ||||||||||||||||||||||||||
24 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK |