Diagnostic Test Mode II (Front HO2S Monitor)

In this mode, MIL displays fuel mixture condition (lean or rich), as monitored by front HO2S. MIL is on when mixture is lean and off when mixture is rich. Therefore, a flashing MIL indicates closed loop fuel control and a MIL that remains on or off indicates open loop.

To check front HO2S function, start engine in diagnostic test mode II. See ENTERING DIAGNOSTIC TEST MODE II (FRONT HO2S MONITORING)  . Warm engine to normal operating temperature. Run engine at 2000 RPM for 2 minutes. MIL should come on more than 5 times within 10 seconds with engine running at 2000 RPM.