Check engine light

I've got a P0125 and P1135 check engine light errors. Which means on my 1999 Camry LE 4cyl. A/F sensor is bad I believe. My question is where is the best place to get this sensor. At Toyota or can I get an after market one. There is a big difference in price. I would appreciate any advice. Thanks tljjersey

I'd try cleaning it before i bought a new one. Its a plastic sensor that plugs into or basically pushes into the plastic box containing your air filter spary some carb cleaner on it and wipe it off you may get lucky if not i saw one for sale on ebay. Also check out discounttoyotaparts.com

Thanks for the info. But this sensor is located on my exhust manafold and is called air/fuel heater sensor. I know you need a special tool just to get is out.