DTC DETECTION LOGIC NOTE： DTC P1148 or P1168 is displayed with DTC for A/F sensor 1. When the DTC is detected, perform the trouble diagnosis of DTC corresponding to A/F sensor 1.

DTC No. | Trouble diagnosis name | DTC detecting condition | Possible cause
P1148 | Closed loop control function (bank 1) | The closed loop control function for bank 1 does not operate even when vehicle is being driven in the specified condition. |

- Harness or connectors
  (The A/F sensor 1 circuit is open or shorted.)
- A/F sensor 1
- A/F sensor 1 heater

P1168 | Closed loop control function (bank 2) | The closed loop control function for bank 2 does not operate even when vehicle is being driven in the specified condition.