P1451

Diagnostic Chart:

Circuit Description

The Barometric Pressure Sensor reading is displayed from the Powertrain Control Module (PCM) at ignition switch ON, engine OFF and at wide open throttle. The Barometric Pressure Sensor represents barometric pressure and is used to compensate for altitude changes.


Conditions for Setting the DTC

Comparison with the Manifold Absolute Pressure (MAP) sensor:

^ Difference between barometric pressure and manifold absolute pressure is 67 kPa or more.

^ Key ON for 2 seconds and engine cranked for 2 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

^ 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.

^ Note that barometric pressure varies depending on weather conditions as well as altitude.

If a DTC P1451 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 Electrical Diagrams.

Test Description

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 fault is present. Review Freeze Frame data to determine when the DTC set. Always record this information. If any MAP DTC's are set, diagnose those DTC's first.