P0450
2GR-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0450: Evaporative Emission Control System Pressure Sensor / Switch
DTC P0450 - Evaporative Emission Control System Pressure Sensor / Switch
DTC P0451 - Evaporative Emission Control System Pressure Sensor Range / Performance
DTC P0452 - Evaporative Emission Control System Pressure Sensor / Switch Low Input
DTC P0453 - Evaporative Emission Control System Pressure Sensor / Switch High Input
DTC SUMMARY
HINT: The pressure sensor is built into the pump module.
DESCRIPTION
HINT: The canister is located near the fuel tank, underneath the body.
While the engine is running, if a predetermined condition (closed-loop, etc.) is met, the purge VSV is opened by the ECM and fuel vapors stored 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 negative pressure (vacuum) is applied to the canister.
The following two monitors run to confirm appropriate EVAP system operation.
1. Key-off monitor
This monitor checks for EVAP (Evaporative Emission) system leaks and 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 electric vacuum 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 pump module and purge VSV, based on the EVAP pressure.
HINT: *: If the engine coolant temperature is not below 35°C (95°F) 5 hours after the ignition switch is turned off, the monitor check starts 2 hours later. If it is still not below 35°C (95°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 two monitors. The 1st monitor is always conducted every time and the 2nd monitor is activated if necessary.
- The 1st monitor
While the engine is running and the purge VSV (Vacuum Switching Valve) 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 is 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.
MONITOR DESCRIPTION
1 DTC P0450: Pressure sensor abnormal voltage fluctuation
If the pressure sensor voltage output rapidly fluctuates between less than 0.45 V and more than 4.9 V, the ECM interprets this as an open or short circuit malfunction in the pressure sensor or its circuit, and stops the EVAP (Evaporative Emission) system monitor. The ECM then illuminates the MIL and sets the DTC (1 trip detection logic).
2 DTC P0451: Pressure sensor abnormal voltage fluctuation or being constant
If the pressure sensor voltage output fluctuates rapidly for 10 seconds, the ECM stops the EVAP system monitor. The ECM interprets this as the pressure sensor voltage fluctuating, and stops the EVAP system monitor. The ECM then illuminates the MIL and sets the DTC.
Alternatively, if the sensor voltage output does not change for 10 seconds, the ECM interprets this as the sensor being stuck, and stops the monitor. The ECM then illuminates the MIL and sets the DTC. (Both the malfunctions are detected by 2 trip detection logic.)
3 DTC P0452: Pressure sensor voltage low
If the pressure sensor voltage output is below 0.45 V, the ECM interprets this as an open or short circuit malfunction in the pressure sensor or its circuit, and stops the EVAP system monitor. The ECM then illuminates the MIL and sets the DTC (1 trip detection logic).
4 DTC P0453: Pressure sensor voltage high
If the pressure sensor voltage output is 4.9 V or more, the ECM interprets this as an open or short circuit malfunction in the pressure sensor or its circuit, and stops the EVAP system monitor. The ECM then illuminates the MIL and sets the DTC (1 trip detection logic).
OBD II MONITOR SPECIFICATIONS
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
All:
P0451 (Noise monitor):
P0451 (Stuck monitor):
P0450, P0452 and P0453:
TYPICAL MALFUNCTION THRESHOLDS
(a) P0450: Pressure sensor chattering
(b) P0451: Pressure sensor noise
(c) P0451: Pressure sensor stuck
(d) P0452: Pressure sensor low voltage
(e) P0453: Pressure sensor high voltage
WIRING DIAGRAM
INSPECTION PROCEDURE
NOTICE:
- When a vehicle is brought into the workshop, leave it as it is. Do not change the vehicle condition. For example, do not tighten the fuel tank cap.
- Do not disassemble the pump module.
- The intelligent tester is required to conduct the following diagnostic troubleshooting procedure.
PROCEDURE
1. CONFIRM DTC AND EVAP PRESSURE
(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch to the ON position (do not start the engine).
(c) Turn the tester on.
(d) Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.
(e) Read the DTCs.
(f) Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DATA LIST / PRIMARY / VAPOR PRESSURE.
(g) Read the EVAP (Evaporative Emission) pressure displayed on the tester.
Result:
C -- GO TO EVAP SYSTEM
B -- REPLACE CHARCOAL CANISTER ASSEMBLY
A -- Continue to next step.
2. CHECK HARNESS AND CONNECTOR (PUMP MODULE - ECM)
(a) Turn the ignition switch off.
(b) Disconnect the E5 ECM connector.
(c) Measure the resistance between the PPMP terminal of the ECM connector and body ground.
Result:
(d) Reconnect the ECM connector.
B -- REPLACE ECM
A -- Continue to next step.
3. CHECK HARNESS AND CONNECTOR (PUMP MODULE - ECM)
(a) Disconnect the L5 canister connector.
(b) Disconnect the E5 ECM connector.
(c) Measure the resistance between the PPMP terminal of the ECM connector and body ground.
Result:
(d) Reconnect the canister connector.
(e) Reconnect the ECM connector.
B -- REPLACE CHARCOAL CANISTER ASSEMBLY
A -- Continue to next step.
4. REPLACE CHARCOAL CANISTER ASSEMBLY
(a) Replace the charcoal canister assembly Removal.
(b) Connect the intelligent tester to the DLC3.
(c) Turn the ignition switch to the ON position and turn the tester on.
(d) Wait for at least 60 seconds.
(e) Select the following menu items on the tester: DIAGNOSIS / ENHANCED OBD II / DTC INFO / PENDING CODES.
HINT: If no pending DTC is displayed on the tester, the repair has been successfully completed.
NEXT -- COMPLETED
5. CHECK HARNESS AND CONNECTOR (PUMP MODULE - ECM)
(a) Disconnect the L5 canister connector.
(b) Turn the ignition switch to the ON position.
(c) Measure the voltage and resistance of the L5 canister connector.
Standard:
Result:
(d) Reconnect the canister connector.
B -- REPAIR OR REPLACE WIRE HARNESS OR CONNECTORS
A -- Continue to next step.
6. REPLACE CHARCOAL CANISTER ASSEMBLY
(a) Replace the charcoal canister assembly Removal.
(b) Connect the intelligent tester to the DLC3.
(c) Turn the ignition switch to the ON position and turn the tester on.
(d) Wait for at least 60 seconds.
(e) Select the following menu items on the tester: DIAGNOSIS / ENHANCED OBD II / DTC INFO / PENDING CODES.
HINT: If no pending DTC is displayed on the tester, the repair has been successfully completed.
NEXT -- COMPLETED
7. REPAIR OR REPLACE WIRE HARNESS OR CONNECTORS
(a) Repair or replace the wire harness or connectors.
(b) Connect the intelligent tester to the DLC3.
(c) Turn the ignition switch to the ON position and turn the tester on.
(d) Wait for at least 60 seconds.
(e) Select the following menu items on the tester: DIAGNOSIS / ENHANCED OBD II / DTC INFO / PENDING CODES.
HINT: If no pending DTC is displayed on the tester, the repair has been successfully completed.
NEXT -- COMPLETED
8. REPLACE ECM
(a) Replace the ECM Removal.
(b) Connect the intelligent tester to the DLC3.
(c) Turn the ignition switch to the ON position and turn the tester on.
(d) Wait for at least 60 seconds.
(e) Select the following menu items on the tester: DIAGNOSIS / ENHANCED OBD II / DTC INFO / PENDING CODES.
HINT: If no pending DTC is displayed on the tester, the repair has been successfully completed.
NEXT -- COMPLETED