The P1451 code is a manufacturer-specific powertrain code primarily associated with Ford vehicles. It indicates an issue with the Evaporative Emission (EVAP) Control System.
Specifically related to the canister vent solenoid circuit. This code is triggered when the Powertrain Control Module (PCM) detects a malfunction in the EVAP system’s ability to properly control fuel vapor emissions.
What Does Code P1451 Mean?
OBD-II Code P1451 is defined as a “Evap Emission Control Sys Vent Control Valve Circuit”.
The EVAP system needs to consistently monitor the solenoid circuit, which is responsible for changing important components of the ECM.
The circuit should send back a specific signal whenever it’s requested for one, and the parameters for that signal are set within the ECM or powertrain control module (PCM).
If that signal isn’t within the specified parameters, then the ECM or PCM will be aware that there’s a problem, which will trigger the code.
Potential Causes of a P1451 Code
Frequent causes of the P1451 code include:
- Damaged or faulty canister vent solenoid
- Open or shorted canister vent solenoid circuit
- Damaged wiring harness or connectors
- VPWR (Vehicle Power) circuit open
- Faulty PCM (rare)
What are the Common Symptoms of the P1451 Code?
- The check engine light is on.
- The vehicle may drive normally, but the check engine light is on.
- The vehicle may fail an emissions test.
- The vehicle may have poor acceleration.
- The vehicle may have decreased overall performance.
How to Diagnose the P1451 Code?
- Connect an OBD-II scanner and verify the P1451 code.
- Check for additional related codes.
- Inspect the wiring harness and connectors for damage, particularly near the canister bracket.
- Test the canister vent solenoid:
- Measure resistance (typically around 62 ohms)
- Apply voltage to check for plunger movement
- Monitor EVAP canister vent solenoid signal (EVAPCV) and voltage:
- Open valve: 0% duty cycle, voltage ≈ battery voltage.
- Closed valve: 100% duty cycle, minimum 4V drop.
- Use output test mode to switch the solenoid on/off.
- Check the VPWR circuit for continuity and proper voltage.
How to Fix the P1451 Code?
- Locate the canister vent solenoid near the fuel tank.
- Disconnect the battery.
- Inspect wiring for damage.
- If wiring is damaged:
- Cut out damaged section
- Solder in new wire
- Use heat shrink tubing for insulation
- If replacing solenoid:
- Disconnect electrical connector
- Remove mounting bolts (typically 10mm)
- Install new solenoid
- Torque bolts to manufacturer specifications (usually 7-10 Nm or 5-7 ft-lbs)
- Reconnect the battery and clear codes.
Safety precautions: Ensure the vehicle is on level ground and properly supported. Use insulated tools when working with electrical components.
How Much Does it Cost to Fix a P1451 Code?
To fix a P1451 code, which typically indicates a faulty EVAP canister vent solenoid, you can expect to pay between $100 and $300 on average, with the cost primarily depending on the labor involved to access and replace the solenoid, as well as the specific vehicle make and model.