P0450
Evaporative Emission (EVAP) System Pressure Sensor Circuit:
Evaporative Emission (EVAP) System Pressure Sensor Circuit (continued):
Evaporative Emission (EVAP) System Pressure Sensor Circuit:
Circuit Description
The fuel tank pressure sensor responses to changes in fuel tank pressure or vacuum. The fuel tank pressure sensor signal voltage to the PCM varies from a minimum of about 0.2 volts with pressure in the fuel tank to above 4 volts with a high vacuum situation in the fuel tank (vent solenoid stuck closed).
Conditions for Running the DTC
^ Vehicle speed greater than 15 km/h (10 mph) for 1 minute.
^ Fuel tank level is between 25 and 75%.
Conditions for Setting the DTC
^ Input range check - voltage less than 0.5 volts.
^ Input range check - voltage greater than 4.8 volts.
^ condition present for 0.5 seconds.
Action Taken When the DTC Sets
^ The Malfunction indicator Lamp (MIL) will illuminate after two consecutive ignition cycles in which the diagnostic runs with the fault active.
^ The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame buffer.
Conditions for Clearing the MIL/DTC
^ The MIL will turn "OFF" after three consecutively passing cycles without a fault present.
^ A History DTC will clear after 40 consecutive warm-up cycles without a fault.
^ DTC(s) can be cleared by using a scan tool or by disconnecting the PCM battery feed.
Diagnostic Aids
Check The Following Conditions:
^ Poor connection at PCM. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.
^ Damaged harness. Inspect the wiring harness for damage.
^ Plugged sensor air vent hole. Inspect sensor and clean if necessary.
^ If multiple DTC(s) are set it may be possible to have an open or shorted reference voltage circuit or an open ground circuit.
^ DTC P0108, P0113, P0118, P0123 and P0450 are set together it is possible to have an open ground circuit (LT. GRN/BLK wire).
^ DTC P0107, P0122 and P0450 are set together it is possible to have an open reference circuit (LT. GRN wire).
If DTC P0450 cannot be duplicated, the information included in the Freeze Frame data can be useful in determining vehicle operating conditions when the DTC was first set.
If any wiring repairs need to be made, Refer to Repair
Procedures in Diagrams.
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
2. Determine if a fault is present. Review Freeze Frame data to determine the condition of when the DTC set. Always record this information.
8. Verifies that the fuel tank pressure sensor accurately reacts to Evaporative Emissions (EVAP) system pressure changes. This also checks the sensor signal input circuit.
10. Checks the operation of the tank pressure control valve.