HB1 - Continuous DTC 0171, 0172, 0174, 0175 Check For Other DTC

Diagnostic Trouble Codes (DTCs) 0171, left bank, and DTC 0174, right bank, indicate the fuel/air ratio is too lean. The system is at the rich limit. DTC 0172, left bank, and DTC 0175, right bank, indicate the fuel/air ratio is too rich. The system is at the lean limit.

Possible Causes:
- Fuel pressure.
- Air Intake/System.
- Crankcase ventilation.
- Engine vacuum.
- HO2S/Injector harness.

- Are other DTCs present?

YES -- SERVICE as required.

NO -- GO to HB2. HB2 - Check Air Intake System