Code
P0133
Emissions
O2 sensor slow response — Bank 1 Sensor 1
The upstream oxygen sensor responds too slowly.
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Most likely causes
- Aging O2 sensor
- Contaminated sensor
- Exhaust leak
Symptoms you may notice
- Check engine light
- Worse economy
Checks to run
- Watch O2 switching rate
- Test the sensor
- Check for leaks
Tools you may need
OBD-II scanner
Multimeter
Always diagnose before replacing. Codes share symptoms; confirm the cause with measurements before buying parts.
Related codes in Emissions
P0420