I have a Rheem Criterion II gas furnace. The unit starts and runs okay most of the time. However it will stop occasionally and will go into 1-hour lockout mode (based on light codes) . What is causing unit to work properly sometimes and not others?

I have checked the orange flame light. It appears to be on steady.
(When running) I cleaned it as described. It is currently working but it's hard to say if that is due to the handy work or just dumb luck. Any other suggestions?

Wait and see. Timed lockouts are usually related to ignition faults, such as dirty flame sensors. If this is what you cleaned, credit your handywork if the problem disappears. Otherwise, if the problem is gone, sometimes it's better to be lucky than to be good!

So far so good, yet it has only been about 16 hours. Yes, I failed to state clearly that it was the flame sensor that I had cleaned (as described in a separate posting).
We'll soon see I guess... Thanks for your help!

Also, 16x28x4 filters for this thing... are they made from gold? $30 a piece, one is on its way - but I now have a good idea why it hasn't been changed regularly.

Rheem model rgph07eauer goes into 1 hour lock out