Understanding Ford Code P1420: Technical Definition
The P1420 trouble code is a generic OBD2 code specific to Ford vehicles that indicates a problem with the fuel vapor recirculation system, specifically concerning the EVAP system (Enhanced Evaporative System) vent valve control circuit. This crucial system controls and recycles gasoline vapors in the tank to reduce polluting emissions.
Operation of the EVAP System in Ford
The EVAP system in Ford vehicles is designed to capture and store gasoline vapors from the tank in an activated carbon filter (canister). When engine operating conditions allow, the engine control unit (ECU) commands the vent valve (EGRV – Evaporative Emission Canister Vent Valve) to open, allowing fresh air to enter the system while the purge valve directs the vapors to the intake to be burned in the engine.
Specific Role of the EGRV Valve
The EVAP canister vent valve plays an essential role in regulating system pressure. It opens to allow ventilation during purge phases and closes during system leak tests. A malfunction of this valve or its electrical circuit immediately triggers the P1420 code and illuminates the check engine light.
Symptoms and Consequences of P1420 Fault
When the P1420 code appears, several characteristic symptoms can alert the driver. Recognizing these signs allows for faster diagnosis and appropriate intervention.
Visible and Perceptible Symptoms
- Check engine light illuminated continuously
- Noticeable increase in fuel consumption
- Persistent gasoline odor around the vehicle
- Unstable or irregular idle
- Difficulty starting in hot weather
- General decrease in engine performance
Long-Term Consequences
Ignoring a P1420 code can lead to more serious problems: contamination of the carbon filter, premature wear of intake system components, and especially failure in technical inspection due to excessive polluting emissions. In some cases, overpressure in the tank can damage fuel lines.
Step-by-Step Technical Diagnosis of Code P1420
Diagnosing the P1420 code requires a methodical approach and the use of appropriate tools. Here is the procedure recommended by Ford experts.
Equipment Needed for Diagnosis
- Ford-compatible OBD2 scanner
- Precision digital multimeter
- Manual vacuum pump
- Vehicle repair manual
- Basic disassembly tools
- Test light for electrical tests
Electrical Diagnosis Steps
Start by checking the condition of the EGRV valve electrical circuit:
- Disconnect the valve’s electrical connector
- Measure the supply voltage with the ignition on
- Check the ground circuit continuity
- Check the valve coil resistance (typically between 20 and 40 ohms)
- Visually inspect the wiring for any damage
EGRV Valve Functional Tests
Once electrical integrity is confirmed, proceed with functional tests:
- Apply 12V directly to the valve to verify its opening/closing
- Test the closed valve’s seal with a vacuum pump
- Verify that the valve opens correctly under vacuum
- Check the proper operation of the ventilation system
Repair Solutions and Corrective Procedures
Depending on the cause identified during diagnosis, several solutions are available to the technician. Most repairs can be performed with standard tools.
Repairing Electrical Problems
If an electrical problem is identified:
- Repair or replace damaged cables
- Clean oxidized connectors
- Replace blown fuses
- Reset the engine control unit after repair
Replacing the EGRV Valve
If the valve is defective, proceed with replacement:
- Locate the EGRV valve (usually near the tank or carbon filter)
- Disconnect the electrical connector
- Disconnect the ventilation lines
- Remove the fasteners and take out the old valve
- Install the new valve following the correct installation direction
- Reconnect all elements and test the operation
Final Checks and Reset
After any repair, perform final checks:
- Clear trouble codes with the OBD2 scanner
- Perform a drive cycle to allow OBD2 monitors to reset
- Verify that the check engine light does not come back on
- Check for absence of leaks in the EVAP system
- Test vehicle performance on the road
Prevention and Maintenance of the Ford EVAP System
To prevent the recurrence of the P1420 code, regular preventive maintenance of the EVAP system is essential.
Good Maintenance Practices
- Avoid topping off the tank after the gas pump clicks
- Replace the carbon filter according to recommended intervals
- Regularly inspect EVAP lines for cracks
- Clean electrical connectors during scheduled maintenance
- Use an OBD2 scanner to monitor system status
Specialized Recommendations
Modern EVAP systems are sensitive to pressure variations and contaminants. It is recommended to have the entire system checked during each major service and to use only certified Ford replacement parts to ensure perfect compatibility and optimal performance.