P0450
1GR-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 canister pressure sensor is built into the canister pump module.
DESCRIPTION
NOTE: The canister is located near the fuel tank, underneath the body.
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 two monitors run to confirm appropriate EVAP system operation.
1. Key-off monitor
This monitor checks for EVAP (Evaporative Emission) 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 enough time for the fuel to cool down to stabilize the fuel tank pressure, thus making the EVAP system monitor more accurate.
The electric 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°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.
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
(a) DTC P0450: Canister pressure sensor voltage abnormal fluctuation
If the canister 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 canister 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).
(b) DTC P0451: Canister pressure sensor noise or stuck
If the canister pressure sensor voltage output fluctuates rapidly for 10 seconds, the ECM stops the EVAP system monitor. The ECM interprets this as noise from the canister pressure sensor, 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).
(c) DTC P0452: Canister pressure sensor voltage low
If the canister pressure sensor voltage output is below 0.45 V, the ECM interprets this as an open or short circuit malfunction in the canister 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).
(d) DTC P0453: Canister pressure sensor voltage high
If the canister pressure sensor voltage output is 4.9 V or more, the ECM interprets this as an open or short circuit malfunction in the canister 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).
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
P0451 (Noise monitor):
P0451 (Fixed monitor):
P0450, P0452 and P0453:
TYPICAL MALFUNCTION THRESHOLDS
P0450: Canister pressure sensor chattering
P0451: Canister pressure sensor noise
P0451: Canister pressure sensor voltage fixed
P0452: Canister pressure sensor low voltage
P0453: Canister 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 cap.
- Do not disassemble the canister pump module.
- The Techstream is required to conduct the following diagnostic troubleshooting procedure.
PROCEDURE
1. CONFIRM DTC AND EVAP PRESSURE
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch ON (do not start the engine).
(c) Turn the tester ON.
(d) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
(e) Read DTCs.
(f) Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Vapor Pressure Pump.
(g) Read the EVAP (Evaporative Emission) pressure displayed on the tester.
Result:
C -- GO TO EVAP INSPECTION PROCEDURE
B -- CHECK HARNESS AND CONNECTOR (CANISTER PUMP MODULE - ECM)
A -- Continue to next step.
2. CHECK HARNESS AND CONNECTOR (CANISTER PUMP MODULE - ECM)
(a) Turn the ignition switch OFF.
(b) Disconnect the E8 ECM connector.
(c) Measure the resistance between the PPMP terminal of the ECM connector and the body ground.
Result:
(d) Reconnect the ECM connector.
B -- REPLACE ECM
A -- Continue to next step.
3. CHECK HARNESS AND CONNECTOR (CANISTER PUMP MODULE - ECM)
(a) Disconnect the L1 canister connector.
(b) Disconnect the E8 ECM connector.
(c) Check the resistance between the PPMP terminal of the ECM connector and the body ground.
Result:
(d) Reconnect the canister connector.
(e) Reconnect the ECM connector.
B -- REPAIR OR REPLACE HARNESS AND CONNECTOR
A -- REPLACE CANISTER ASSEMBLY
4. CHECK HARNESS AND CONNECTOR (CANISTER PUMP MODULE - ECM)
(a) Disconnect the L1 canister connector.
(b) Turn the ignition switch ON.
(c) Measure the voltage and resistance of the L1 canister connector.
Standard:
Result:
(d) Reconnect the canister connector.
B -- REPAIR OR REPLACE HARNESS AND CONNECTOR
A -- REPLACE CANISTER ASSEMBLY
5. REPLACE CANISTER ASSEMBLY
(a) Replace the canister assembly (Removal).
NOTE: When replacing the canister, check the canister pump module interior and related pipes for water, fuel or other liquids. If liquids are present, check for disconnections and/or cracks in the following: 1) the pipe from the air inlet port to the canister pump module;2) the canister filter; and 3) the fuel tank vent hose.
NEXT -- CHECK WHETHER DTC OUTPUT RECURS (AFTER REPAIR)
6. REPAIR OR REPLACE HARNESS AND CONNECTOR
HINT: If the exhaust tail pipe has been removed, go to the next step before reinstalling it.
NEXT -- CHECK WHETHER DTC OUTPUT RECURS (AFTER REPAIR)
7. REPLACE ECM
NEXT -- CHECK WHETHER DTC OUTPUT RECURS (AFTER REPAIR)
8. CHECK WHETHER DTC OUTPUT RECURS (AFTER REPAIR)
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch ON and turn the tester ON.
(c) Wait for at least 60 seconds.
(d) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes / Pending.
HINT: If no pending DTC is displayed on the tester, the repair has been successfully completed.
NEXT -- COMPLETED