From Ross-Tech Wiki

17544/P1136/004406 - Fuel Trim: Bank 1 (Add): System too Lean

Possible Solutions

  • Check Mass Air Flow (MAF) Sensor
  • Check Fuel Pressure Regulator
  • Check Fuel Pump
  • Check Intake/Exhaust System for Leaks
  • Check Secondary Air Injection for Leaks
  • Check Vacuum Lines for Leaks

Special Notes

  • Fuel Trim Info
  • When this fault is stored and external vacuum leaks are not found, less obvious problems may be present:
    • Check Evaporative Emission (EVAP) Canister Purge Regulator Valve (N80)
    • Check Brake Booster and Hoses
    • Check Electric Vacuum Pump ( If Applicable )
    • Check Crankcase Ventilation System for faulty components. When the PCV or Crankcase Ventilation System is faulty, vacuum is typically present under the oil cap and misfire faults are common.