Advanced Diagnostics
DTC P0451 (91) Advanced Diagnostics
DTC P0451:
Fuel Tank Pressure (FTP) Sensor Circuit Range/Performance Problem
General Description
The fuel tank pressure (FTP) sensor is installed on the evaporative emission (EVAP) canister. The FTP sensor is used to detect leaks in the EVAP system. The powertrain control module (PCM) monitors the FTP sensor output voltage. The FTP sensor output voltage rises as the fuel tank pressure increases. Conversely, the FTP sensor output voltage drops as the fuel tank pressure decreases. Rapid changes in the FTP sensor output voltage due to electrical noise or an intermittent open during the EVAP leak detection may cause incorrect leak detection, so abnormal output is monitored. If the FTP sensor output voltage change occurs for specified ratio within a set time, the PCM detects a malfunction and stores a DTC.
Monitor Execution, Sequence, Duration, DTC Type, OBD Status
Enable Conditions
Malfunction Threshold
The FTP sensor output voltage fluctuation occurs for more than 30 % within the set time at least 33 seconds.
Driving Pattern
1. Start the engine, and let it idle until the radiator fan comes on.
2. Drive the vehicle at a steady speed 35 mph (56 km/h) or more for at least 10 seconds.
3. Decelerate with the throttle valve fully closed.
4. Repeat Driving Pattern steps 2 through 3, three times.
- Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.
Diagnosis Details
Conditions for setting the DTC
When a malfunction is detected during the first drive cycle, a Pending DTC is stored in the PCM memory. If the malfunction returns in the next (second) drive cycle, the MIL comes on and the Confirmed DTC and the freeze data are stored.
Conditions for clearing the DTC
The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the battery.