OBD codes / P0133
P0133
ModerateO2 Sensor Circuit Slow Response (Bank 1, Sensor 1)
P0133 is generally safe to drive with short-term — it mostly affects fuel trim and emissions, not whether the car runs. Replace the aging sensor when convenient to restore economy and pass emissions. If contamination is suspected, address what's fouling it so the replacement lasts.
What this code means
A healthy upstream oxygen sensor switches quickly between rich and lean as it fine-tunes fueling. P0133 means the Bank 1, Sensor 1 sensor is responding too slowly — it's gotten lazy. The most common cause is simply an aging sensor (they wear out and slow down over time). It can also be contamination (from oil, coolant, or silicone sealant) or an exhaust leak near the sensor that throws off its readings. A slow sensor hurts fuel economy and emissions, so it's worth replacing.
Symptoms you might notice
- Check-engine light, often with no obvious change
- Reduced fuel economy
- Occasional rough running or hesitation
- Failed emissions test
What it costs to fix
Typical range: $150–$500 · about ~0.3–1.5 hrs of labor
| If the cause is… | Part | Labor |
|---|---|---|
| Upstream oxygen (O2) sensor | $50–$250 | ~0.3–1 hrs |
| Exhaust leak repair near the sensor | $20–$200 | ~0.5–2 hrs |
A slow-responding sensor is almost always replaced, a low-hundreds job. A seized or buried sensor adds labor, and OEM sensors on some makes cost more than aftermarket. If contamination caused it, fix the source (oil/coolant) so the new sensor doesn't fail too.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P0133 for my exact vehicle →
Frequently asked
Can I drive with P0133?
Usually yes, short-term — it mainly affects fuel economy and emissions. Replace the sensor reasonably soon to restore efficiency and pass an emissions test.
Does P0133 mean a new O2 sensor?
Most often, yes — a slow (lazy) response is the classic sign of an aging sensor. Just rule out an exhaust leak near it and check the wiring first, and if contamination fouled it, fix that source too.
What contaminates an oxygen sensor?
Oil or coolant burning in the exhaust, or the wrong silicone sealant nearby, can coat the sensor and slow it down. If a sensor failed from contamination, fixing the leak that caused it keeps the new one from failing.
How much does it cost to fix P0133?
Usually a low-hundreds sensor replacement. It rises if the sensor is seized or hard to reach, or if the real cause is an exhaust leak that needs a gasket or weld.
Seeing P0133 on your car? Get a diagnosis specific to your exact year, make and model.
Diagnose P0133 for my vehicleGeneric OBD-II reference. Manufacturer-specific behavior varies — confirm with a scan tool and, for safety-related codes, a professional inspection.