P0450

Diagnostic Chart:

Wiring Diagram:

Circuit Description

The fuel tank pressure sensor responds 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 is 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.

^ DTCs can be cleared by using a scan tool or by disconnecting the PCM battery feed.

Diagnostic Aids

Check for any of the following conditions:

^ A plugged sensor air vent hole. Inspect the sensor and clean if necessary.

^ When a DTC P0108, P0113, P0118, P0123 and P0450 are set together check for an open ground circuit (LT. GRN/BLK wire).

^ When a DTC P0107. P0122 and P0450 are set together check for an open reference circuit (LT. GRN wire).

^ Road test the vehicle while observing the fuel tank pressure sensor parameter on a scan tool. A momentary reading of -59.0 mm Hg (-31.5 in. H2O) may indicate an intermittent short to ground in the sensor signal circuit while a momentary reading of 60.0 - 61.5 mm Hg (32 - 33 in. H2O) may indicate an intermittent open in any of the sensor circuits.

^ A poor connection at the PCM. Inspect the harness connectors for backed out terminal, improper mating, broken locks, improperly formed or damaged terminals, and a poor terminal to wire connection.

^ A damaged wiring harness. Inspect the wiring harness for damage and repair as necessary.

If the 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 last set. This may assist in determining how often the DTC sets.

If any wiring repairs need to be made, Refer to Repair Procedures in Electrical Diagrams.

Test Description

The numbers below refer to the step numbers 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 the Freeze Frame data to determine the condition of when the DTC set. Always record this information.

9. Verifies that the fuel tank pressure sensor accurately reacts to EVAP system pressure changes. This also checks the sensor signal input circuit.

11. Checks the operation of the fuel tank pressure control valve. For additional functional checks, Refer to Enhanced Emission (EVAP) Control System. Evaporative Emissions System

12. Checks the operation of the fuel tank pressure control valve. For additional functional checks, Refer to Enhanced Emission (EVAP) Control System. Evaporative Emissions System