Reading OBD II Diagnostic Trouble Codes (DTC)

(1) OBD II reader reports 2 errors codes when ignition switch is turned on.

(2) Pressing the "Read" button shows the first error code. P0155 = "O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)".

(3) Pressing the "Read" button again shows the second "pending" error code. The diagnostic trouble code (DTC) is again P0155, implying that the P0155 error has occurred more than once.