What does code P1166 mean on Hyundai vehicles?
The ECU detects that the control limit has been reached for the upstream oxygen sensor on Bank 1, indicating fuel mixture correction is at its limit.
OBD-II Code Hyundai
P1166 — Hyundai — Heated Oxygen Sensor (HO2S) 1 Bank 1 Control Limit Reached
The ECU detects that the control limit has been reached for the upstream oxygen sensor on Bank 1, indicating fuel mixture correction is at its limit.
Common symptoms
- Check engine light illuminated
Possible causes
- Air-fuel mixture out of range
- intake leaks
- aged oxygen sensor
Initial recommendation
Inspect air-fuel mixture, check for vacuum leaks and test oxygen sensor operation.
Safety notice
This information is for guidance only. Brand-specific codes may vary by model, year, engine, transmission and vehicle configuration. It does not replace a physical inspection or diagnosis by a qualified mechanic. If the vehicle is unsafe to operate, avoid driving it and seek professional inspection.
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