Fault code P0451 – a step-by-step guide to diagnosing and fixing it

Error code P0451 is displayed and the check engine light is on - what does this mean?

DTC P0451 is triggered by the OBD system when the fuel tank pressure sensor (FTP sensor) sends a low voltage signal to the engine control unit. This fault code relates to the evaporative emission system (EVAP) and may have slightly different names for different manufacturers, but always refers to the fuel tank pressure sensor.

What causes can this error code have?

• Defective fuel tank pressure sensor (FTP sensor)
• Damaged or corroded cable connections to the pressure sensor
• Loose or defective plug connections on the sensor
• Short circuit in the sensor wiring
• Defective engine control unit (ECM/PCM)
• Blocked or damaged vacuum lines to the sensor
• Mechanical damage to the sensor due to stone chips or corrosion

What symptoms occur in parallel with fault code P0451?

• Check engine light: The check engine light is permanently illuminated
• Starting problems: Occasional difficulties starting the engine, especially when the engine is warm
• Idle irregularities: Erratic idling or fluctuating engine speed
• Fuel odor: Smell of gasoline around the vehicle, especially after refueling
• Emission test problems: Vehicle may not pass emissions test
• Power loss: Slight loss of engine power at higher speeds

How to fix the problem of trouble code P0451?

• Repairing trouble code P0451 requires a systematic approach to identify the exact cause.
• Complete replacement of the FTP sensor: Replace the defective fuel tank pressure sensor with a new original part, including all seals and fastening elements
• Sensor wiring repair: Check and repair all wiring connections to the pressure sensor, including soldering damaged wires and replacing corroded connectors
• Cleaning and maintenance of connectors: Clean all electrical connections with contact spray and re-establish secure contact
• Replacing the wiring harness: In the event of serious cable damage, replace the entire wiring harness between the sensor and control unit
• Check and replace vacuum lines: Check all vacuum hoses for cracks or blockages and replace damaged lines
• Engine control unit diagnostics: Have the ECM/PCM tested by a specialist and repaired or replaced if necessary