Code 91

Front Heated O2 Sensor Test:

FRONT HEATED OXYGEN SENSOR (DTC: P0135)
1) Start engine and run it for at least 35 seconds in idle condition.
2) Turn ignition switch "OFF", wait for at least 3 seconds and then "ON".

Switching Test Modes:

3) Perform "Diagnostic Test Mode II (Self-diagnostic results)" with ECCS Control Module.