P0133 on a Toyota: Causes, Fixes & Repair Cost

🟠 Moderate severity · drivable

A Toyota with P0133 usually still drives fine, but fuel economy may drop slightly until the sensor is replaced.

What P0133 means on a Toyota

On a Toyota, P0133 means the bank 1 upstream sensor is responding too slowly. Toyota calls this sensor an air-fuel ratio (A/F) sensor rather than a regular oxygen sensor, and the computer uses it to fine-tune the fuel mixture.

Is P0133 common on Toyotas?

P0133 is common on higher-mileage Toyotas like the Camry, Corolla, and RAV4. The A/F sensor ages with mileage, and because it's a wide-range sensor, replacement parts cost more than on brands that use plain oxygen sensors.

Commonly reported on: Camry, Corolla, RAV4, Highlander.

Symptoms

Check engine light on
Slightly worse fuel economy
Rough idle or hesitation
Failed emissions test

Common causes

most common: Aging air-fuel ratio sensor (bank 1, sensor 1)
common: Exhaust leak before the sensor
common: Contaminated sensor from oil or coolant
less common: Wiring or connector damage at the sensor

How to fix it

Fix	DIY?	Typical cost
Check for exhaust leaks and repair them before replacing the sensor	Yes	$50–200
Replace the upstream A/F sensor with a quality part	Yes	$120–300
Have the sensor wiring and connector repaired if damaged	Mechanic	$100–250