P0133: Upstream O2 sensor slow response (Bank 1 Sensor 1)
Drive carefully. Get it checked within a week or two.
Can I drive with P0133?
Yes, but drive carefully and get it checked soon. The sensor is aging and sluggish, delaying fuel trim corrections and hurting gas mileage.
What does P0133 mean?
P0133 stands for O2 Sensor Circuit Slow Response (Bank 1, Sensor 1).
Symptoms you may notice
- Drop in gas mileage by 10% to 15%
- Slight hesitation or sluggish response when accelerating
- Check engine light illuminated
How much does it cost to fix?
Repair costs for code P0133 depend on the specific underlying root cause, ranging from simple DIY checks to component replacement. The table below lists the most common causes and rough price ranges in USD:
- Aging, soot-coated oxygen sensor
- Exhaust manifold or flex pipe leak
- Dirty MAF sensor causing skewed fuel maps
- Contamination from burning engine oil
What to do next
- Check for exhaust leaks near the manifold flanges and flex pipe.
- Replace the upstream Bank 1 oxygen sensor (they typically last 80,000-100,000 miles).
- Clear the code and conduct a drive cycle to verify switching speed.
Last updated: October 2026
Related codes
General guidance only, not a professional diagnosis. If the check-engine light is flashing, or the car is running rough, overheating or losing power, stop driving and get help.
About this code
Code P0133 indicates an aged oxygen sensor that switches too slowly between rich and lean. Known in the automotive trade as a 'lazy sensor,' it responds sluggishly to throttle changes. The car remains fully drivable, but you will notice a 10% to 15% drop in fuel economy over time. Replacing the sensor restores crisp throttle response.