P0102
DTC P0102CIRCUIT DESCRIPTION
The mass air flow (MAF) sensor is an air flow meter that measures the amount of air entering the engine. The MAF sensor used on this vehicle is a hot film meter (HFM) type. The engine control module (ECM) uses the MAF sensor signal in order to provide the correct fuel delivery for a wide range of engine speeds and loads. The MAF sensor signal is a function of the current required to keep the air flow sensing element at a fixed temperature. The air flowing through the sensor cools the sensing element. The amount of cooling is proportional to the amount of the air flow. As the air flow increases, more current is required in order to maintain the hot film at a constant temperature. The MAF sensor converts the changes in current to a voltage signal that is read by the ECM. The ECM calculates the air flow based on this voltage signal. The MAF sensor uses the following circuits in order to operate:
- The ignition 1 voltage
- The 5-volt reference
- The MAF sensor signal
- The low reference
The 5-volt reference for the MAF sensor is also supplied to additional sensors. For each of the sensors, the voltage is supplied on separate ECM terminals. The terminals are connected within the ECM to the same stabilized sensor supply voltage. The 5-volt reference is shared by the following sensors:
- The MAF sensor
- The accelerator pedal position (APP) sensor 1
- The fuel tank pressure (FTP) sensor
- The air conditioning (A/C) refrigerant pressure sensor
The low reference circuit of the MAF sensor is shared with the following components:
- The camshaft position (CMP) sensor
- The intake air temperature (IAT) sensor
- The engine coolant temperature (ECT) sensor
If the ECM detects the MAF sensor signal is less than the possible range of a properly operating sensor, DTC P0102 sets.
CONDITIONS FOR RUNNING THE DTC
- The ECM has counted more than 20 crankshaft revolutions.
- The engine speed is more than 300 RPM.
- The engine has been running for more than 0.5 seconds in order to allow the MAF sensor hot film element to heat up.
- The ignition 1 signal is more than 10 volts.
CONDITIONS FOR SETTING THE DTC
- The ECM detects that the MAF sensor signal is less than 0.42 volt for more than 2 seconds.
OR
- The MAF sensor signal is less than a calculated value using throttle position (TP) and engine speed.
ACTION TAKEN WHEN THE DTC SETS
- 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.
CONDITIONS FOR CLEARING THE MIL/DTC
- 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.
- Clear the MIL and the DTC with a scan tool.
DIAGNOSTIC AIDS
- Inspect for the following conditions:
- A high resistance on any of the MAF sensor circuits except the low reference may cause this DTC to set intermittently and also result in poor engine performance.
- A high resistance on the 5-volt reference of the MAF sensor may result in poor engine performance without setting this DTC.
- A low minimum air rate through the sensor bore may cause this DTC to set at idle or during deceleration. Inspect for any vacuum leaks downstream of the MAF sensor.
- Any contamination of the hot film element of the MAF sensor may cause this DTC to set.
- A wide-open throttle acceleration from a stop should cause the MAF sensor g/s display on the scan tool to increase rapidly. This increase should be from 3-7 g/s at idle to 72 g/s or more at the time of the 1-2 shift. If the increase is not observed, inspect for a restriction in the Induction System or the Exhaust System.
- If the condition is intermittent, refer to Intermittent Conditions. Diagnostic Strategies
TEST
Steps 1-3:
Step 4:
Steps 5-6:
Steps 7-11:
Step 12:
Steps 13-15:
