Diagnostic Procedure
NOTE:
If DTCs P0444, P0445, P0447 or P0448 are also set, diagnose these DTCs first. See DTC P0444: EVAP PURGE VALVE CONTROL CIRCUIT OPEN , DTC P0445: EVAP PURGE VALVE CONTROL CIRCUIT SHORTED , DTC P0447: EVAP VENT VALVE CONTROL CIRCUIT OPEN or DTC P0448: EVAP VENT VALVE CONTROL CIRCUIT SHORTED
.
- Turn ignition on, engine off. Remove fuel cap. Using scan tool, monitor FUEL TANK PRESS. SENSOR. If voltage is 1.3-1.7 volts, go to next step. If voltage is less than 0.1 volt, see DTC P0452: EVAP FUEL TANK PRESSURE SENSOR CIRCUIT - LOW VOLTAGE . If voltage is 0.1-1.3 volts or 1.7-4.9 volts, replace fuel tank pressure sensor. If voltage is greater than 4.9 volts, see DTC P0453: EVAP FUEL TANK PRESSURE SENSOR CIRCUIT - HIGH VOLTAGE .
- Install fuel cap. Using scan tool, perform EVAP SYSTEM SEAL. Connect EVAP Pressure/Purge Diagnostic Cart (J 41750-SAT) to EVAP service port. Pressurize system to 8 in. H2O, then switch to hold position. Use ultrasonic leak detector to locate small leaks. See DIAGNOSTIC AIDS .