I have a honda civic 96 .yesterday its yellow light on seedometer became on.I am worried about this.please inform me about this.thanks

It's called a Check Engine Light and it indicates one or more Diagnostic Trouble Codes (DTCs) are stored in the ECM (computer). Attach a code reader to the Data Link Connector, located under the dash, and read the code(s). Many AutoZone stores will do this for free.

Any code reader will work--some cost $40 or less (Harbor Freight). Here's a list of possible codes:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-4.html#post325940

It could be any number of issues. To diagnose it, a honda certified computer must be hooked up to your car to see what code is reading. Typically, if the light is solid, it is no big deal. If the check engine light is flashing, then take it directly to your preferred mechanic to diagnose the issue. Sometimes though, it is a loose gas cap. Make sure the gas cap is on tight... 3 clicks... drive for about 50 miles and it should reset, if that is the issue. Your car will not pass insepction with the check engine light lit, so it is something you will eventually have to get diagnosed. Hope this helps.