95 Avalon OBD-I CEL, how to check the code and the EGR valve?

[rice h8r]

The check engine light has been on my car for a while and I've been too lazy to check it since it's OBD-1. I tried searching, but it looks like the search function isn't working. Does anyone know the procedure and a list of possible codes?
I have a hunch it has to do something with an o2 sensor or possibly the EGR valve. Is it hard to take it off and clean it? I don't want to take it off and not know how it goes back on if there's a specific method. It's the circle looking thing by the throttle body, right?

Also another quick thing, do you guys have problems with the engine burning oil? I seem to be loosing a quart every 2000/3000 miles. There are no external leaks and the valve cover gaskets have been done already. The car has 131K on it.
The coolant reservoir also always seems to be empty. I fill it up to the max line and the next time I check it, maybe a couple of weeks later and it's empty again. Does that little tube on top allow coolant flow back and forth between the tank and the engine? If so, coolant and oil disappearing = slow internally leaking headgasket[s]?

Thanks in advance for helping a n00b out. I still have to change the front rotors [warped] and the sway bar bushings and endlinks.

[toyomoho]

The 1995 Avalon may have ODBII, Toyota started the change over before the mandated time. Your easier method is to get the codes read.

Burning 1 quart every 2-3K is not bad, the engine may be just burning oil. Be sure to check for leaks with the engine running.

You need to check the complete cooling and heater system for leaks. The upper and lower radiator tanks are plastic and can crack resulting in at first very small leaks. Check the radiator for signs of coolant or the dye left behind after it evaporates.

Check all the hoses including the heater and bypass for coolant leaks. With the engine cold, feel the hoses for coolant. The reservoir tank can crack and leak. Check the carpet under the heater core, the core can leak (passengers side).

Yes, the hose transfer coolant back and forth between the reservoir.

You may have a head gasket leak, the easiest method is to test for exhaust gases in the coolant. Or could be a slow leak somewhere else.

[rice h8r]

^ Hey thanks for the response. The engine is bone dry, I don't see any leaks in the engine bay or underneath the car and nothing drips onto the ground where the car is parked. I'll look around though next time when the engine is hot and running.

If it has OBD-II, where is the port located? I guess I'll have to look around under the dash and hope there's one so I can just get it scanned.

[toyomoho]

Below steering column and to the left.

Have someone do a test for exhaust gases in the coolant or buy a test kit from an auto parts shop.