Hi I'm planning to buy a used junkyard oem gen3 prius cat for my prius. I was wondering how can I tell if its oem or aftermarket? is this the correct o2 parts I see the review some people say it dont work for gen3 prius? downsteam o2 - DENSO 2344400 upstream o2 - DENSO 234-9301 is there any aftermarket gasket and bolts for the cat or I have to get oem?
The oem cat includes the exhaust heat recirculation system and bolts in. If it is aftermarket it will be just the front two cats crudely welded into the factory exhaust recirculation system. Most likely you can reuse your bolts and gaskets or the junkyard parts. A junkyard assembly will have the sensors as well. The only caution on any of this is if the engine(s) were oil burners the cats may be fouled.
Look at you're old cat on way out of car see at the front wer exhaust first hits honeycomb. Look for clogging plugging. Hold up to sun look into cat carefully . Bingo. If you're at an exhaust shop tell him to tell ya what he sees on you're old .