Question

The light went off by itself then P0420 came on. I smelling gas bad, and gas is being used faster, I have a 1998 Honda Accord LX 2.3L

Answer 1

This code is for a faulty catalytic converter. If the engine is burning to rich it could cause this code to appear. Since the timing light did go off by itself, I think I would check and change the oil, and also check the spark plugs. If they are old and worn out the engine may not be operating at it's best. This can leave raw gas that will cause the code from the converter.

Answer 2

P0420 HONDA Code - Catalyst System Efficiency Below Threshold Bank 1
Read more: https://www.autocodes.com/p0420_honda.html