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Error Code P1448 is defined as EVAP Canister Vent Control Valve Open.
This error code is a manufacturer-specific trouble code, meaning it does not apply to all vehicles makes. Rather, it applies only to specific vehicle makes, such as Nissan. Specification on the definition, troubleshooting, and repairs still vary from one make and model to another.
Located on the EVAP canister, the EVAP canister vent control valve works by sealing the canister vent. It’s a solenoid valve that responds to the signals from the PCM (powertrain control module, also known as ECM or engine control module). The coil in the solenoid valve is energized when the PCM sends On signal. A plunger will move to seal the canister vent. This ability to seal the vent is essential for the on-board diagnosis of the components of Evaporative Emission Control System.
This solenoid valve is used only for diagnosis, and usually, remains open. If the vent is closed, under normal purge conditions, the evaporative emission control system is depressurized and allows EVAP control system (small leak) diagnosis.
This error code is detected when the EVAP canister vent control valve remains open under specified driving conditions.
As with other error codes, this code activates the Check Engine light and registers the code to the vehicle’s system.
This error can be caused by multiple factors, such as:
- EVAP canister vent control valve
- EVAP canister is saturated with water
- EVAP control system pressure sensor and the circuit
- Blocked rubber tube to EVAP canister vent control valve
- Water separator
How to Check
To accurately diagnose this error code, some wiring tests must be performed, which in most cases require serious knowledge of automotive wiring to do it properly. If you’re not confident with your automotive knowledge and skills, it is best to take your vehicle to your dealer and have this problem fixed by professionals.
Should you want to try to diagnose the problem yourself, here’s how you can check:
Start by checking the damage to the EVAP canister or hoses. If no hoses are damaged, then the problem must be in the EVAP canister control valve, which means it must be replaced.
Start the diagnosis by turning the ignition off and then disconnecting the EVAP canister vent control harness connector. Then, switch the ignition on, use a DVOM to measure the voltage between the EVAP canister vent control valve harness connector terminal number 1 (brown wire) and the ground. If there’s battery voltage, head to the next step. If there is no battery present, check and repair for a blown fuse, open or short in Brown wire.
Turn the ignition off, then disconnect the PCM harness connector. Check for continuity between the PCM harness connector terminal no. 108 and EVAP canister vent control valve harness connector terminal number 2 (purple wire). Use the DVOM. If there’s no continuity, repair open or short in the purple wire between the PCM and the EVAP canister vent control valve.
Then, check and repair rubber tube to the EVAP canister vent control valve for any obstructions or damages. Check the EVAP canister control valve. If there are no faults, check the PCM harness connector for signs of corrosions or damages to the terminal. Repair as necessary.
How to Fix
Repair or replace damaged EVAP canister or hoses.
Replace canister control valve
Many times, Error Code P1448 can be accompanied by Error Code P0440. The latter refers to evaporative leak, which means the vehicle has found a leak in the EVAP system.