Fuel Injection
Air Fuel Ratio Sensor
An air fuel ratio sensor measures oxygen in the exhaust so the engine computer can set the fuel mixture precisely. We carry 35 air fuel ratio sensors from $56 to $404 for 1997-2021 vehicles. Denso and NGK make most of them, and Honda leads the fitment list with the Accord and CRV, followed by Toyota Camry and Nissan.
Shop air fuel ratio sensor by vehicle
Denso Upstream Air Fuel Ratio Sensor 234-9014 for Honda Accord
Fits 2001–2002 models
Denso Upstream Air Fuel Ratio Sensor W0133-1606912 for Honda Accord
Fits 1999 models
Denso Upstream Air Fuel Ratio Sensor W0133-1606912 for Honda Accord
Fits 2000 models
What the sensor does
An air fuel ratio sensor is a wide band version of an oxygen sensor. It sits in the exhaust before the catalytic converter and gives a precise reading for lean, ideal and rich mixtures, rather than just rich or lean.
A failing sensor often sets a check engine light with codes for the sensor circuit, heater circuit or fuel trim. You may notice poorer fuel economy, rough idle or a failed emissions test. A slow sensor can also lead to catalytic converter damage over time.
Upstream, downstream and bank
Air fuel ratio sensors are usually upstream, before the converter. Some vehicles use a standard oxygen sensor downstream. Our listings include upstream, upstream right, upstream rear and downstream positions.
On V6 and V8 engines, each bank has its own upstream sensor, so read the code to learn which bank is at fault. Wiring harness length varies, from about 19.75 in to 40.5 in in these listings, so match it to the original routing.
Install tips
Work on a warm, not hot, engine so the threads release more easily, and use an oxygen sensor socket. Most new sensors come with anti seize on the threads. Keep it off the sensor tip.
Use the vehicle selector and read the fitment table for engine and emissions version, since California and federal models can differ. Clear the codes after install and drive normally so the computer can relearn fuel trims.
Air Fuel Ratio Sensor questions
Is an air fuel ratio sensor the same as an oxygen sensor?
They do a similar job, but an air fuel ratio sensor reads a wider range with more precision. They are not interchangeable, so buy the type your engine uses.
Which air fuel ratio sensor is bank 1?
Bank 1 is the side of the engine with cylinder number one. The location varies by engine, so check a service manual or engine diagram for your model.
Can a bad air fuel ratio sensor hurt fuel economy?
Yes. If the sensor reads incorrectly, the computer may add too much fuel, which lowers mileage and can damage the catalytic converter over time.