Engine knocking - rocker arms or EGR valve?

0ojoyo00ojoyo0 Member Posts: 1
edited June 2015 in Isuzu
Please bear with me – I know nothing about cars. I bought a '99 Trooper 3.5L with 187k miles for cheap, and I knew it needed a lot of work. It has engine knocking coming from the passenger side and I know nothing about the maintenance, other than it recently had a new camshaft, head, and oil pump, and the next thing that could be causing the tapping is the rocker arms – this is coming from the previous owner’s mechanic. The CEL is on, solid not blinking, and I took it to AutoZone to get read – it came back with an EGR valve error (code P0401). The knocking sounds more like soda can in a bike tire spokes (remember doing this as a kid?) and is present when the truck idles and gets faster/louder at 2k rpms. My question is, could this just be the EGR valve causing the knocking and is it possible that rocker arms aren’t an issue at all? I am going to change the oil this weekend with synthetic 5w-30, and am planning on putting premium gas in, based on all I’ve read on the forums. Is it ok to keep driving with the CEL and knocking? This is my second vehicle – just for hauling big stuff and trash runs, so I figured I would run it into the ground and that would be it, but if it’s an easy/cheap fix, I’d rather do that instead. TIA!
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