P0101
DTC P0101
CIRCUIT DESCRIPTION
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 to provide the correct fuel delivery for a reduction in emissions. The ECM uses the MAF sensor signal 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 the inlet air flow through the air induction system. This output voltage will display on the scan tool as a voltage parameter and as a grams per second (g/s) parameter. 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. If the ECM detects that the actual MAF sensor voltage signal is not within a predetermined range of the calculated MAF value, DTC P0101 sets.
DTC DESCRIPTOR
This diagnostic procedure supports the following DTC:
DTC P0101 Mass Air Flow (MAF) Sensor Performance
CONDITIONS FOR RUNNING THE DTC
- DTC P0016, P0102, P0103, P0112, P0113, P0116, P0117, P0118, P0234, P0237, P0238, P0299, P0335, P0336, P0340, P0341, P0370, P0374, P2227, P2228, P2229 are not set.
- The ignition 1 signal is between 9-18 volts.
- The intake air temperature (IAT) is more than -20°C (-4°F).
- The engine speed is less than 3,500 RPM.
- The engine speed is steady within a range of 50 RPM.
- The engine coolant temperature (ECT) is more than -20°C (-4°F).
- The above conditions are met for more than 2 seconds.
- DTC P0101 runs continuously within the enabling conditions.
CONDITIONS FOR SETTING THE DTC
The ECM detects that the MAF sensor voltage signal is not within a predetermined range of the calculated MAF value for more than 12 seconds.
ACTION TAKEN WHEN THE DTC SETS - CALIFORNIA
- 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.
ACTION TAKEN WHEN THE DTC SETS - FEDERAL
- 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.
CONDITIONS FOR CLEARING THE MIL/DTC - CALIFORNIA
- 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.
CONDITIONS FOR CLEARING THE DTC - FEDERAL
- 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.
DIAGNOSTIC AIDS
- Any unmetered air that enters the engine downstream of the MAF sensor may cause this DTC to set.
- A short between the signal circuit of the MAF sensor and the signal circuit of the intake air temperature (IAT) sensor will skew the MAF sensor higher than normal at idle and less than normal at higher air flows.
- A malfunctioning MAF sensor can cause excessive engine emissions.
- The MAF display should increase from 24-50 g/s at idle to 320 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 Inducing Intermittent Fault Conditions and Intermittent Conditions. Intermittent Conditions
TEST
Steps 1-7:
Steps 8-13:
Steps 14-24:
