DTC P0451
DTC P0451 : Evaporative Emission (EVAP) Leak Check Module Pressure Sensor Range/Perfomance
General Description
The powertrain control module (PCM) detects abnormal output of the evaporative emission (EVAP) leak check module pressure sensor since the output changes excessively due to electricity noise interruption and or open circuit during the EVAP system leak detection, it will affect the diagnosis of the purge flow. If the EVAP leak check module pressure sensor value continues to fluctuate while the purge is not flowing, the PCM detects a malfunction and stores a DTC.
Monitor Execution, Sequence, Duration, DTC Type
| Execution | Continuous |
| Sequence | None |
| Duration | 32 seconds or more |
| DTC Type | Two drive cycles, MIL on |
Enable Conditions
| Condition | Minimum | Maximum |
|---|---|---|
| Elapsed time after starting the engine | 10 seconds | - |
| Engine coolant temperature [ ECT Sensor 1 ] | 131 deg.F (55 deg.C) | - |
| 12 volt battery voltage [ Battery ] | 10.5 V | - |
| EVAP canister purge valve duty [ EVAP PC Duty ] | 0 % | |
| Fuel feedback | During deceleration | |
| Other | Purge-cut operation | |
| [ ] : HDS Parameter | ||
Malfunction Threshold
The fluctuation of EVAP leak check module pressure sensor output is detected for a rate of 94 % during 32 seconds.
Possible Cause
The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
- EVAP leak check module ELCMPA line layer open
- EVAP leak check module VCC6 line layer open
- EVAP leak check module SG6 line layer open
- EVAP leak check module pressure sensor electrical noise over lapped
- EVAP leak check module pressure sensor internal circuit failure
Confirmation Procedure
Operating Condition
- Start the engine, and let it idle until the radiator fan comes on.
- Drive the vehicle at a steady speed 35 mph (56 km/h) for at least 10 seconds.
- Decelerate with the throttle valve fully closed.
- 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 a Confirmed DTC, the freeze data, and the on-board snapshot 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, the freeze data, and the on-board snapshot can be cleared with the scan tool clear command.