Oxygen sensor circuit slow response — Bank 1 Sensor 1
The controller determined that the upstream oxygen-sensor feedback changed more slowly than expected during its test.
Conditions that can produce P0133
These are diagnostic branches, not a ranked parts list. Prevalence and testing order depend on the exact vehicle and failure scene.
- Aged, contaminated, or incorrect sensor
- Heater performance or supply problem
- Exhaust leak ahead of the sensor
- Fuel-control or airflow problem slowing the transition
- Wiring resistance, connector, or ground fault
What to inspect next
- Identify the exact sensor type and correct data interpretation
- Review heater codes and circuit evidence
- Check for exhaust leakage and mixture faults
- Perform the exact response test rather than counting generic voltage switches
Evidence that strengthens the answer
Verify the repair
Preserve the pre-repair record, document exactly what changed, then repeat the relevant operating condition safely. Confirm no current or pending fault returns, review permanent-code and readiness state where applicable, and state which tests or modules remained unavailable.
This page explains a commonly standardized code at a general level. Confirm the exact definition, module, status, test conditions, thresholds, wiring, and service process for the vehicle application using current official information.