P0133 Code: O2 Sensor Circuit Slow Response (Bank 1 Sensor 1)

🟠 Moderate severity · drivable

Drivable, but the slow fuel-control feedback hurts economy and emissions.

What P0133 means

The bank 1 upstream oxygen sensor is switching too slowly in response to exhaust changes. A healthy upstream sensor flips its signal quickly; a sluggish one is usually aging or contaminated, so the computer's fuel correction lags behind the engine's actual needs.

Symptoms

Check engine light on
Reduced fuel economy
Possible failed emissions test

Common causes

most common: Aging or contaminated upstream oxygen sensor
common: Exhaust leak near the sensor
less common: Oil or coolant contamination of the sensor

How to fix it

Fix	DIY?	Typical cost
Replace the bank 1 upstream oxygen sensor	Yes	$60–200
Repair an exhaust leak near the sensor	Mechanic	$50–200

Frequently asked questions

What does 'slow response' mean?

The sensor takes too long to switch between rich and lean readings, which usually means it's wearing out or contaminated.

Is P0133 usually the sensor?

Yes. A slow-responding upstream sensor almost always needs to be replaced.

How much does it cost to fix P0133?

Typically $60–$200 for a new oxygen sensor.

Related codes

P0130 Code: O2 Sensor Circuit Malfunction (Bank 1 Sensor 1)

P0131 Code: O2 Sensor Circuit Low Voltage (Bank 1 Sensor 1)

P0132 Code: O2 Sensor Circuit High Voltage (Bank 1 Sensor 1)

P0133 by vehicle brand

Causes and repair costs for P0133 differ between makes. Pick your brand for the specifics.

P0133 on a Toyota

P0133 on a Honda

P0133 on a Ford

P0133 on a Chevy

P0133 on a Nissan

P0133 on a Mercedes-Benz

P0133 on a Volkswagen

P0133 on a Hyundai

P0133 on a Subaru

P0133 on a Mazda

P0133 on a Jeep

P0133 on a Lexus

P0133 on a Volvo

Related guide: MAF Sensor Replacement Cost →

Updated 2026-08. This page is informational and not a substitute for professional diagnosis.