P0133Medium severity
O2 Sensor Circuit Slow Response (Bank 1 Sensor 1)
The upstream oxygen sensor on bank 1 is responding too slowly to changes in the air-fuel mixture.
Common causes
- Aging/contaminated oxygen sensor
- Exhaust leak
- Wiring problems
Possible symptoms
- Check Engine Light on
- Reduced fuel economy
- Failed emissions test
Code breakdown
P — System
Powertrain (engine, transmission, fuel & emissions)
0 — Type
Generic (SAE standard, common to all manufacturers)
1 — Subsystem
Fuel and air metering