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2011 KIA OPTIMA
2.4L I4•FWD•AUTOMATIC•gas
5 active safety recalls on this vehicle — view recalls
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Repairs0Labor548Torque4528Fluid6DTC893Battery1Maintenance0Recalls5
P1166moderate severityPowertrain

HO2S Bank 1 Sensor 1 Control Limit Reached

on 2011 Kia Optima 2.4L I4 · FWD

What this code means

The PCM has detected that the fuel control correction based on the Bank 1 upstream O2 sensor has reached its maximum limit. The PCM can no longer adequately compensate for the air-fuel ratio deviation.

Symptoms

  • Check Engine Light
  • Poor fuel economy
  • Rough idle
  • Hesitation
  • Failed emissions test

Common causes

  • Large vacuum leak
  • Faulty upstream O2 sensor
  • Exhaust leak before sensor
  • Fuel pressure out of range
  • MAF sensor malfunction

Diagnostic steps

  1. Check fuel trim values on scan tool for direction of correction
  2. Test for vacuum leaks
  3. Monitor O2 sensor switching
  4. Check fuel pressure
  5. Inspect MAF sensor

Repair notes

Repair the underlying air-fuel ratio issue causing the control limit to be reached.

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🔧 Database maintained under the daily editorial review of Chris Hackleman · Master Technician · 20+ years and Jeff Moore · Master Lexus & Toyota Mechanic · 20+ years. Spot an error? Use the Help link above — a human reads every report.
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