I bought a 99 durango 5.9 4x4 sport pkg. The old owner put flowmaster exhaust on it. Well here's the deal, i get 2 codes p0505 and p0171.

So i go ok new o2 sensor is needed, and go out to look under the truck to see how many i have to replace.. I have NO o2 sensors anywhere on the exhaust, but i do have the cat on it

I'm sure this thing came with o2 sensors? If so how to add them back to the system.

 

your truck would not run right without a pre-cat oxygen sensor, id be very surprised if at least that one isnt there

that second code says to me that the sensor is either in line and reading wrong (needs replacement) or just hanging outside the pipe and reading no unburnt fuel bc its not seeing the exhaust flow look around for loose wires and empty plugs see what turns up

the first code is pretty self explanatory

 

Yeah, well i ran my hand all the way up to the manifold on both sides and there is no sensors in the exhaust. I'll have to look around for wires next time I get a chance to crawl under it.

 

I found them, and shrp you where correct. It did have one be for the cat. It was just mounted in the top of the exhaust, and will be a major pain to get it.