I just bought a 2000 Honda Passport. The next day the engine check light came on. I need to replace EGR valve, thermostat, and possible oxygen sensor. I don't have the money to have someone to do so would like to do myself. Any help would be grateful or ideals? Thanks very much.

I believe that is an Isuzu with a Honda badge on it. Google your topics or go to You Tube and search there. I found a great video for my Honda CRV.

That would require hacking into the ECU and changing the programming.

How would I replace EGR valve on a 2000 Honda Passport? Would that be replacing spark plugs, coil, and wires?

Up front I have to say: I'm all for people trying to do things themselves but sometimes a little bit of knowledge is dangerous. If you're not sure what an EGR valve is, where it is, what it looks like, and why you need to clean it...it may really be better to get it to someone that can do it. Ask around, everyone knows someone that can fix cars and you may find someone that is knowledgeable enough about this to help you out so you don't make anything worse.

With that said, I will attempt an answer to your question.
Why do you need to replace it?
Also, note that many times the EGR valve may seem bad but the passages are blocked by carbon build up. If this is the case, simply replacing the valve will not solve the problem and you will have wasted your time and money. An EGR valve has nothing to do with spark plugs, coils, and wires.

This is a video for an Isuzu Rodeo but these are essentially the same things. The whole video includes how to clean the valve itself. Be sure to clean the surfaces on the valve and the intake and replace the gasket with a new one. EGR Valve Cleaning - 2001 Isuzu Rodeo - YouTube