On-Board Diagnostics

WARNING: This page is about a different car, the 2002 Isuzu Trooper. However, it is still accessible from the selected car via links, so may be relevant.

A diagnostic test is a series of steps, the result of which is a pass or fail reported to the Diagnostic Executive. When a diagnostic test reports a pass result, the Diagnostic Executive records following data:

Diagnostic test has been completed since last ignition cycle.
Diagnostic test has passed during current ignition cycle.
Fault identified by diagnostic test is not currently active.

When a diagnostic test reports a fail result, the diagnostic executive records the following data:

Diagnostic test has been completed since last ignition cycle.
Fault identified by diagnostic test is currently active.
Fault has been active during this ignition cycle.
Operating conditions at time of failure.

A fuel trim DTC may be triggered by a list of vehicle faults. Make use of all information available (other DTCs stored, rich or lean condition, etc.) when diagnosing a fuel trim fault.