ignition problem

I have a '90 honda accord ex. I have an ignition problem that is intermittent. It starts most of the time but on occasion(3-4 x per week)
thr engine light stays on while starting and it just turns over without any ignition at all. The problem will last from a few minutes to a few hours. I replaced the plugs , wires, rotor cap & button and cleaned the intake. These changes have not helped the problem.
A mechanic scanned the computer and he tells me that the engine light is a #20 error which he says is an electrical overload that is probably unrelated / minor to the stating problem that i have.
If anyone has had this problem before please give me some ideas on how to troubleshoot and repair the car.
Thanks in Advance

Is it getting fuel when trying to start?

When the car isn't starting, turn the ignition On(do not start) & listen for the fuel pump - you should hear it turn on for about 2 seconds. If no fuel pressure - then your main relay is possibly taking a shit. Faulty main relays are very common & have those similar crank/no start conditions. Its very simple to replace yourself.

If your interior is cold & the car is not starting, try heating the main relay with a blow dryer - if the car starts, replace the relay.

As you stated, "turns over without any ignition at all" - could be a possible bad coil and/or igniter. Has the mechanic checked over the car besides the code?