Circuit Description
The mass airflow (MAF) sensor measures the amount of air entering the engine during a given time. The engine control module (ECM) uses the MAF sensor information to monitor exhaust gas recirculation (EGR) flow rate. A large quantity of air entering the engine indicates an acceleration or high load condition while a small quantity of air indicates a deceleration or idle condition. The ECM has the ability to detect an air intake leak by using the MAF sensor and the EGR control pressure sensor.
Conditions for Running the DTC
| • | DTCs P0101, P0102, P0103, P0112, P0113, P0116, P0117, P0118, P0405, P0406, P0489, P0490, P0500, P0651, P2141, P2142, P2144, P2145, P2227, P2228, P2229 are not set. |
| • | The engine is running for more than 60 seconds. |
| • | The barometric pressure (BARO) sensor pressure is more than 72 kPa (10 psi). |
| • | The ignition 1 voltage is between 9-16 volts. |
| • | The vehicle speed is less than 1.6 km/h (1 mph) |
| • | The engine speed is between 600-700 RPM. |
| • | The coolant temperature is between 0-80°C (32-176°F). |
Conditions for Setting the DTC
| • | The ECM detects an intake leak that is more than the calibrated value, internal to the ECM. |
| • | The condition is met for 2 seconds. |
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
| • | The most likely cause of the DTC is a leaking intake duct after the MAF sensor. |
| • | To run the diagnostic test the following conditions must be met: |
| - | The engine is at full operating temperature. |
| - | The vehicle is in drive. |
| - | The vehicle has been idling for more than 1 minute. |
| • | After meeting these conditions, shift the vehicle into park, and hold the engine speed steady between 1,500-2,100 RPM for 30 seconds. If the diagnostic test still fails to run, the vehicle must be driven. |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views | |||||||||
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 | |||||||
Did the DTC fail this ignition? | Go to Step 4 | Go to Diagnostic Aids | |||||||
4 |
Did you complete the repair? | Go to Step 5 | -- | ||||||
5 |
Did the DTC fail this ignition? | Go to Step 2 | Go to Step 6 | ||||||
6 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | System OK | |||||||
