P0133 on a Honda: Causes, Fixes & Repair Cost

🟠 Moderate severity · drivable

A Honda with P0133 usually still drives well, but fuel economy drops a bit until the sensor is replaced.

What P0133 means on a Honda

On a Honda, P0133 means the bank 1 upstream oxygen sensor is switching too slowly. This sensor measures the exhaust after it leaves the engine, and the computer uses it to keep the fuel mixture on target.

Is P0133 common on Hondas?

P0133 is common on higher-mileage Hondas like the Civic, Accord, and CR-V. The upstream O2 sensor wears out with age, and fixing small exhaust leaks first avoids replacing a sensor that was never the real problem.

Commonly reported on: Civic, Accord, CR-V, Odyssey.

Symptoms

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

Common causes

most common: Aging upstream oxygen sensor (bank 1, sensor 1)
common: Exhaust leak before the sensor
common: Vacuum leak leaning out the mixture
less common: Sensor wiring or connector damage

How to fix it

Fix	DIY?	Typical cost
Check the exhaust and intake for leaks before replacing the sensor	Yes	$50–150
Replace the upstream O2 sensor	Yes	$80–200
Repair the sensor wiring harness if damaged	Mechanic	$100–250