Federal Models

DIAGNOSTIC PROCEDURE

Wiring Diagram Of The Oxygen Sensor Circuit:

NOTE: If Diagnostic Trouble Code "21" is output inspect / replace front Oxygen Sensor. If Diagnostic Trouble Code "28" is output, inspect / replace rear Oxygen Sensor.

1. Are there any other codes, besides code 21 or 28, being output ?
- If YES Go to relevant Diagnostic Trouble Code chart.
- If NO replace Oxygen Sensor.