P0451 Evaporative Emission System Pressure Sensor Range/Performance
The PCM monitors the fuel tank differential pressure sensor output voltage.
The PCM determines whether the fuel tank differential pressure sensor signal voltage is within normal operating parameters.
Test Conditions:
Throttle valve is closed.
Vehicle speed is less than 1.5 km/h (0.93 mph).
Judgment Criteria:
If the voltage signal from the fuel tank differential pressure sensor changes by 0.2 volt or more, DTC P0451 will set. The code may also set if a sudden pressure fluctuation occurs twenty times while the engine is idling, and then eight consecutive times during normal driving.
NOTE: If the number of sudden pressure fluctuations does not reach twenty during any one period of engine idling, or the ignition switch is turned "LOCK" (OFF) position, the counter will reset to zero.
NOTE: The conditions for deviating from idling operation are as follows:
Engine speed is greater than 2,500 r/min.
Vehicle speed is greater than 15 km/h (9.3 mph).
Volumetric efficiency is greater than 55 percent.
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Malfunction of the fuel tank differential pressure sensor.
• A damaged harness in the fuel tank differential pressure sensor circuit.
• Malfunction of the PCM.
OVERVIEW OF TROUBLESHOOTING
DTC P0451 can be set by a faulty fuel tank differential pressure sensor or related circuit, or PCM failure.
To check a system blockage, do a performance test which uses a mechanical vacuum gauge and scan tool MB991502 set on the fuel tank differential pressure sensor (TANK PRS SNSR 73). The mechanical gauge reading is used to verify
scan tool MB991502 reading. A comparison of the mechanical gauge with the
reading on scan tool MB991502 will locate a problem in the system.
The PCM monitors the fuel tank differential pressure sensor output voltage.
The PCM determines whether the fuel tank differential pressure sensor signal voltage is within normal operating parameters.
Test Conditions:
Throttle valve is closed.
Vehicle speed is less than 1.5 km/h (0.93 mph).
Judgment Criteria:
If the voltage signal from the fuel tank differential pressure sensor changes by 0.2 volt or more, DTC P0451 will set. The code may also set if a sudden pressure fluctuation occurs twenty times while the engine is idling, and then eight consecutive times during normal driving.
NOTE: If the number of sudden pressure fluctuations does not reach twenty during any one period of engine idling, or the ignition switch is turned "LOCK" (OFF) position, the counter will reset to zero.
NOTE: The conditions for deviating from idling operation are as follows:
Engine speed is greater than 2,500 r/min.
Vehicle speed is greater than 15 km/h (9.3 mph).
Volumetric efficiency is greater than 55 percent.
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Malfunction of the fuel tank differential pressure sensor.
• A damaged harness in the fuel tank differential pressure sensor circuit.
• Malfunction of the PCM.
OVERVIEW OF TROUBLESHOOTING
DTC P0451 can be set by a faulty fuel tank differential pressure sensor or related circuit, or PCM failure.
To check a system blockage, do a performance test which uses a mechanical vacuum gauge and scan tool MB991502 set on the fuel tank differential pressure sensor (TANK PRS SNSR 73). The mechanical gauge reading is used to verify
scan tool MB991502 reading. A comparison of the mechanical gauge with the
reading on scan tool MB991502 will locate a problem in the system.