The mass air flow (MAF) sensor is an air flow meter that measures the amount of air entering the engine. The engine control module (ECM) uses the MAF sensor voltage signal in order to provide the correct fuel delivery for a reduction in emissions. The ECM uses the MAF sensor signal in order to control fuel delivery until a calibrated amount of engine air flow is attained. The MAF sensor has an ignition 1 voltage circuit, a signal circuit and a low reference circuit. The MAF sensor produces an output voltage based on inlet air flow through the air induction system. This output voltage will display on the scan tool as a grams per second (g/s) value. The ECM will calculate a predicted MAF value. The ECM compares the actual MAF sensor voltage signal to the predicted MAF value. This comparison will determine if the signal is stuck, or is too low or too high for a given operating condition. DTC P0101 will set if the actual MAF sensor voltage signal is not within a predetermined range of the calculated MAF value.
• | DTC P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0234, P0236, P0237, P0238, P0335, P0336, or P1345 are not set. |
• | The ignition 1 signal is between 9-18 volts. |
• | The engine speed is less than 2,500 RPM. |
• | The engine speed is steady within a range of 50 RPM. |
• | The accelerator pedal position (APP) indicated angle is less than 50 percent. |
• | The above conditions are present for more than 2 seconds. |
The ECM detects that the actual MAF sensor voltage signal is not within a predetermined range of the calculated MAF value for more than 2 seconds.
• | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
• | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
• | The control module stores the DTC information into memory when the diagnostic runs and fails. |
• | The malfunction indicator lamp (MIL) will not illuminate. |
• | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records. |
• | The driver information center, if equipped, may display a message. |
• | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
• | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
• | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
• | Use a scan tool in order to clear the MIL and the DTC. |
• | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
• | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
• | Use a scan tool in order to clear the MIL and the DTC. |
Inspect for the following conditions:
• | Any unmetered air--Any unmetered air that enters the engine downstream of the MAF sensor may cause this DTC to set. |
• | A sluggish or unresponsive MAF sensor--A short between the signal circuit of the MAF sensor and the signal circuit of the intake air temperature (IAT) sensor. This will cause the MAF sensor to have a very limited output voltage range. |
• | A malfunctioning MAF sensor can cause excessive engine emissions. |
• | An open on the 5-volt reference circuit of the barometric pressure sensor (BARO) may cause this DTC to set. |
• | A short to ground on the signal circuit of the BARO sensor may cause this DTC to set. |
• | The signal circuit of the BARO sensor shorted to 5 volts may cause this DTC to set. |
• | An open signal circuit of the BARO sensor may cause this DTC to set. |
• | The MAF display should increase from 42-50 g/s at idle to 420 g/s or more at the 2-3 shift during a wide-open throttle (WOT) acceleration. If not, inspect for a restriction in the induction system or the exhaust system. |
• | If the vehicle condition is intermittent, refer to Intermittent Conditions . |
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 | Inspect the fuse in the ignition 1 voltage circuit of the MAF sensor. Is the fuse open? | -- | Go to Step 17 | Go to Step 5 | ||||||||||||||||||||||||||
5 |
Did you find and correct the condition? | -- | Go to Step 26 | Go to Step 6 | ||||||||||||||||||||||||||
6 |
Does the scan tool indicate that the difference between the sensors is equal to or less than the specified value? | 8 kPa | Go to Step 7 | |||||||||||||||||||||||||||
7 |
Does the movement of the harness or the connector affect the MAF sensor g/s? | -- | Go to Step 21 | Go to Step 8 | ||||||||||||||||||||||||||
8 | Observe the MAF sensor g/s with a scan tool. Is the MAF sensor g/s less than the specified value? | 16 g/s | Go to Step 11 | Go to Step 9 | ||||||||||||||||||||||||||
9 | Observe the MAF sensor g/s with a scan tool. Is the MAF sensor g/s more than the specified value? | 445 g/s | Go to Step 10 | Go to Step 11 | ||||||||||||||||||||||||||
10 | Disconnect the harness connector of the MAF sensor. Refer to Mass Airflow Sensor/Intake Air Temperature Sensor Replacement . Is the MAF sensor g/s more than the specified value | 445 g/s | Go to Step 15 | Go to Step 11 | ||||||||||||||||||||||||||
11 |
Does the test lamp illuminate? | -- | Go to Step 12 | Go to Step 17 | ||||||||||||||||||||||||||
12 |
Important: All electrical components and accessories must be turned OFF.
Is the resistance less than the specified value? | 5ohms | Go to Step 13 | Go to Step 18 | ||||||||||||||||||||||||||
13 |
Did the MAF sensor value change to the specified value? | 445 g/s | Go to Step 22 | Go to Step 14 | ||||||||||||||||||||||||||
14 |
Did you find and correct the condition? | -- | Go to Step 26 | Go to Step 16 | ||||||||||||||||||||||||||
15 |
Important:: Disconnecting the ECM connectors may eliminate the short to voltage if the signal circuit is shorted to another ECM circuit.
Does the voltage measure near the specified value? | 0 V | Go to Step 16 | Go to Step 19 | ||||||||||||||||||||||||||
16 | Use a DMM in order to test for continuity at the harness connector of the ECM from the signal circuit of the MAF sensor to all other circuits at both ECM connectors. Refer to Circuit Testing in Wiring Systems. Does the DMM indicate continuity between any other circuit? | -- | Go to Step 20 | Go to Step 23 | ||||||||||||||||||||||||||
17 |
Did you complete the repair? | -- | Go to Step 26 | Go to Step 24 | ||||||||||||||||||||||||||
18 | Repair the high resistance or an open in the low reference circuit of the MAF sensor. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 26 | Go to Step 23 | ||||||||||||||||||||||||||
19 | 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 26 | -- | ||||||||||||||||||||||||||
20 | Repair the circuits that are shorted together. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 26 | -- | ||||||||||||||||||||||||||
21 | Repair the harness or the connections as necessary. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 26 | -- | ||||||||||||||||||||||||||
22 | Inspect for poor connections at the harness connector of the MAF sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 26 | Go to Step 24 | ||||||||||||||||||||||||||
23 | Inspect for poor connections at the harness connector of the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 26 | Go to Step 25 | ||||||||||||||||||||||||||
24 | Replace the MAF/IAT sensor. Refer to Mass Airflow Sensor/Intake Air Temperature Sensor Replacement . Did you complete the Replacement? | -- | Go to Step 26 | -- | ||||||||||||||||||||||||||
25 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the Replacement? | -- | Go to Step 26 | -- | ||||||||||||||||||||||||||
26 |
Does the DTC run and pass? | -- | Go to Step 27 | Go to Step 2 | ||||||||||||||||||||||||||
27 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK |