Code Definition
- DTC P0450: EVAP Pressure Sensor Fault
- DTC P0451: EVAP Pressure Sensor Range/Performance Malfunction
| CAUTION | If ECM replacement is instructed in following testing, always ensure ECM harness connector and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. If ECM is replaced, ECM must be programmed with proper ignition key code for engine immobilizer system. For programming procedures, see COMPUTER RELEARN PROCEDURES - IMPORT article in GENERAL INFORMATION. |
Note. Vapor canister and some related components can be accessed through trunk by removing trunk floor mat and protective access cover at front of trunk. For component location, see appropriate illustration in THEORY & OPERATION article.
Circuit Description
Vapor pressure sensor, canister closed valve Vacuum Switching Valve (VSV) and pressure switching valve VSV are used to detect faults in EVAP system. DTC P0450 is set if 10 seconds after engine starts, vapor pressure sensor reading stays unchanged. DTC P0451 is set if pressure reading at vapor pressure sensor is greater than or equal to pressure of charcoal canister while vehicle is standing at idle and pressure switching valve VSV is off. Possible causes are
- Short or open in vapor pressure sensor circuit.
- Faulty vapor pressure sensor.
- Faulty ECM.
Diagnostic Aids
Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.