engine light comes on in 88 Accord

The Accord in which I recently replaced a radiator (thread http://www.automotiveforums.com/vbulletin/showthread.php?t=962744) has been showing the amber engine. This just started a week or so ago.

What usually causes this?

I've been doing a litte research and I guess I should have known my question was oversimplified. Here's one reference I found: http://www.repairtrust.com/check.html. These engine lights can come on for many reasons. I'll probably have to take to a shop that has a diagostic tool to determine the exact cause.

Somewhere I read that 'check engine' light that comes on especially when the car heats up, that light has something to do with the Main Relay connection. Folks can repiar it themselves via soldering the connections in the main relay.

In my Accord, this light has been on for last 3 years when drive is long and car has heated up. Have not seen any problems in other areas so I did not really fixed it.

Get some one with a scanner and check it out for the real cause.

Somewhere I read that 'check engine' light that comes on especially when the car heats up ...Well, in this case, it comes on soon after the engine is started, even if it's a cold start.

... that light has something to do with the Main Relay connection. Folks can repair it themselves via soldering the connections in the main relay.
Eh, thanks, but no thanks. I think I'll skip the soldering technique.

In my Accord, this light has been on for last 3 years when drive is long and car has heated up. Have not seen any problems in other areas so I did not really fixed it.
Yes, the 88 Accord seems to run normal. So, I'm not viewing this as an urgent matter. But, ideally, I would like to determine the cause.