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P0133

O2 sensor circuit slow response (Bank 1 Sensor 1)

The upstream Bank 1 oxygen sensor is responding more slowly than the ECU expects to changes in air-fuel mixture.

What this code means

The upstream Bank 1 oxygen sensor is responding more slowly than the ECU expects to changes in air-fuel mixture.

Possible causes

  • Aged or contaminated oxygen sensor
  • Exhaust leak
  • Fuel-mixture fault
  • Sensor wiring issue

Common symptoms

  • Check engine light
  • Sluggish response
  • Poor fuel economy
  • Possible rough idle

Checks to make

  1. Review O2 sensor switching activity with live data
  2. Check for exhaust leaks
  3. Check fuel trims and related codes
  4. Inspect sensor wiring

Safety

  • Do not replace parts from the code alone. Confirm the fault with live data, wiring checks and manufacturer procedures. Keep clear of hot or moving engine components.

Model notes

The code definition is generic; exact diagnostic thresholds, component locations and repair procedures vary by vehicle.