Diagnostic Aids

Verify clean, tight connection on G106 (Brown wire).

An intermittent condition may be caused by poor connection, rubbed-through insulation, or a broken wire inside insulation. Check ECM harness connectors for backed-out, improperly mated, broken locks, improperly formed, or damaged terminals, and poor terminal-to-wire connections before component replacement.

Fig 1: Code 27 Schematic (Except LSi) Oxygen Sensor Circuit, Open Or Shorted Circuit

Fig 2: Code 27 Flow Chart (Except LSi) Oxygen Sensor Circuit, Open Or Shorted Circuit