Check engine light?

[motoman]

The vehicle in question is a 2003 Ford Explorer Sport XLT with the v6 engine and here's the back story. A few months back I noticed a really low sound at very low speeds or really low idle. It sounds like it's coming from the exhaust somewhere, possibly an exhaust leak but it does have the go cart like puttering sound. Instead it sounds like I have bass from a couple of 12's or 15 inch subs and I don't. Just last week my check engine light came on and I went up to O'Reilly's to pull the code and it pulled two different codes, p171 & p174. Everything points to about 15 possible things, all most exhaust related somewhere.

I need input on what would throw a check engine light that's exhaust related.


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[thomasblively]

O2 sensors will. I can't remember the code my father in laws was throwing but a new catalytic converter cleared his up. His was making a very similar sound to the one you explained

[motoman]

How easy is it to tell if they're bad and replace them myself?


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[Skidonenko]

How easy is it to tell if they're bad and replace them myself?


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Remove it from the exhaust and see if small pieces com out or if it rattles. You can buy a univeral one with the correct pjpe size to weld in place or an aftermarket direct replacement that will bolt in.

[motoman]

So my check engine light codes were for both engine banks running lean. Replaced the PCV valve and had to pull the intake manifold to replace the gasket. Explorer passed the inspection after that. Turns out the really low drone noise is from my tires.