Check Engine Code
P0133
O2 Sensor Circuit Slow Response (Bank 1, Sensor 1)
Severity: low
DIY difficulty: 2/5
Typical cost: $40–$300
What P0133 means
P0133 means the ECM measured how quickly the O2 sensor swings between rich and lean and found it too sluggish. Sensors degrade over time — most aftermarket sensors last 60-100k miles.
Symptoms
- Check engine light
- Slight fuel economy drop
- Occasionally paired with catalyst codes (P0420)
Likely causes (most common first)
- Aged/worn O2 sensor (most common at 80k+ miles)
- Contaminated sensor (oil burn-off, coolant, bad fuel)
- Exhaust leak near the sensor
- Failing sensor heater circuit
Can I keep driving?
Low — mostly emissions/economy
Typical repair cost
DIY fixes can start near $40 (parts only). Shop repairs for P0133 typically run up to $300 depending on the underlying cause and vehicle. Start with the most common cause — Aged/worn O2 sensor (most common at 80k+ miles) — before throwing parts at it.
Related codes
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