P2402
DTC P2401 Evaporative Emission Leak Detection Pump Stuck OFFDTC P2402 Evaporative Emission Leak Detection Pump Stuck ON
Malfunction Detection Condition (Part 1):
Malfunction Detection Condition (Part 2):
DTC SUMMARY
DESCRIPTION
NOTE: In this vehicle's EVAP system, turning ON the vent valve does not seal off the EVAP system. To check for leaks in the EVAP system, disconnect the air inlet vent hose and apply pressure from the atmosphere side of the canister.
While the engine is running, if a predetermined condition (closed loop, etc.) is met, the purge VSV is opened by the ECM and stored fuel vapors in the canister are purged to the intake manifold. The ECM changes the duty cycle ratio of the purge VSV to control purge flow volume.
The purge flow volume is also determined by the intake manifold pressure. Atmospheric pressure is allowed into the canister through the vent valve to ensure that the purge flow is maintained when the negative pressure (vacuum) is applied to the canister.
The following 2 monitors run to confirm appropriate EVAP system operation.
1. Key-off monitor
This monitor checks for Evaporative Emission (EVAP) system leaks and canister pump module malfunctions. The monitor starts 5 hours. after the ignition switch is turned OFF. More than 5 hours are required to allow the fuel to cool down to stabilize the Fuel Tank Pressure (FTP), thus making the EVAP system monitor more accurate.
The leak detection pump creates negative pressure (vacuum) in the EVAP system and the pressure is measured. Finally, the ECM monitors for leaks from the EVAP system and malfunctions in both the canister pump module and purge VSV, based on the EVAP pressure.
HINT: *: If the engine coolant temperature is not below 35 degrees C (95 degrees F) 5 hours after the ignition switch is turned OFF, the monitor check starts 2 hours later. If it is still not below 35 degrees C (95 degrees F) 7 hours after the ignition switch is turned OFF, the monitor check starts 2.5 hours later.
2. Purge flow monitor
The purge flow monitor consists of the 2 monitors. The 1st monitor is conducted every time and the 2nd monitor is conducted if necessary.
- The 1st monitor
While the engine is running and the purge Vacuum Switching Valve (VSV) is ON (open), the ECM monitors the purge flow by measuring the EVAP pressure change. If negative pressure is not created, the ECM begins the 2nd monitor.
- The 2nd monitor
The vent valve turned OFF (open) and the EVAP pressure is then measured. If the variation in the pressure is less than 0.5 kPa (3.75 mmHg), the ECM interprets this as the purge VSV being stuck closed, and illuminates the MIL and sets DTC P0441 (2 trip detection logic).
Atmospheric pressure check:
In order to ensure reliable malfunction detection, the variation between the atmospheric pressures, before and after conduction of the purge flow monitor, is measured by the ECM.
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INSPECTION PROCEDURE
NOTE: The intelligent tester is required to conduct the following diagnostic troubleshooting procedure.
HINT:
- Using the intelligent tester monitor results enable the EVAP system to be confirmed.
- Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.
MONITOR DESCRIPTION
Monitor Strategy:
Typical Enabling Conditions (Part 1):
Typical Enabling Conditions (Part 2):
Typical Malfunction Thresholds:
5 hours*. after the ignition switch is turned OFF, the leak detection pump creates negative pressure (vacuum) in the EVAP system. The ECM monitors for leaks and actuator malfunctions based on the EVAP pressure.
HINT: *:If the engine coolant temperature is not below 35 degrees C (95 degrees F) 5 hours after the ignition switch is turned OFF, the monitor check starts 2 hours later. If it is still not below 35 degrees C (95 degrees F) 7 hours after the ignition switch is turned OFF, the monitor check starts 2.5 hours later.
1. P2401: Leak detection pump stuck OFF
In operation B, the leak detection pump creates negative pressure (vacuum) through the reference orifice. The EVAP system pressure is then measured by the ECM using the canister pressure sensor to determine the 0.02 inch leak criterion. If the pressure is higher than -1.06 kPa (-7.95 mmHg)*. or lower than -4.85kPa (-36.38 mmHg)*, the ECM interprets this as the leak detection pump being stuck OFF (not operating). The ECM then illuminates the MIL and sets the DTC (2 trip detection logic).
*: The threshold varies according to the atmospheric pressure measured in operation A. The values described above are based on an atmospheric pressure of 100 kPa (750.1 mmHg): absolute pressure.
2. P2402: Leak detection pump stuck ON
In operation B, the leak detection pump creates negative pressure (vacuum) through the reference orifice. The EVAP system pressure is then measured by the ECM using the canister pressure sensor to determine the 0.02 inch leak criterion. If the pressure is higher than -1.06 kPa (-7.95 mmHg)* or lower than -4.85 kPa (-36.38 mmHg)* , the ECM interprets this as the leak detection pump being stuck ON (operating all the time). The ECM illuminates the MIL and sets the DTC (2 trip detection logic).
*: The threshold varies according to the atmospheric pressure measured in operation A. The values described above are based on an atmospheric pressure of 100 kPa (750.1 mmHg): absolute pressure.
HINT: The detection logic of DTCs P2401 and P2402 is the same because in both cases the 0.02 inch leak criterion measured in operation B is compared to the atmospheric pressure registered in operation A. The ECM calculates the difference between these pressures by deducting [the 0.02 inch leak criterion] from [the stored atmospheric pressure], and uses this to monitor the EVAP system pressure change.
MONITOR RESULT
Refer to detailed information. Mode 6 Data