Check Engine Code
P0133
O2 Sensor Circuit Slow Response (Bank 1, Sensor 1)
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.
Symptoms that match P0133
If you got here from a search query, one of these might describe what your car is actually doing:
Related codes
Confirm P0133 yourself in 60 seconds
AXLY.pro is a free iPhone app that pairs with any Bluetooth OBD2 adapter to read P0133 and every other stored code, plus live engine data. No subscription.