1998 Honda Prelude Owner's Manual - Page 239

Malfunction Indicator Lamp If you have recently refueled your vehicle, the cause of this indicator coming on could be a loose or missing fuel fill cap. Check the cap and tighten it until it clicks. Replace the fuel fill cap if it is missing. Tightening the cap will not make the indicator turn off immediately; it takes three driving trips. If the indicator remains on past three driving trips, or the fuel cap was not loose or missing, have the vehicle checked by the dealer as soon as possible. Drive moderately until the dealer has inspected the problem. Avoid full-throttle acceleration and driving at high speed. You should also have the dealer inspect your vehicle if this indicator comes on repeatedly, even though it may turn off as you continue driving. MALFUNCTION INDICATOR LAMP NOTICE If you keep driving with the malfunction indicator lamp on, you can damage your vehicle's emissions controls and engine. Those repairs may not be covered by your vehicle 's warranties. This indicator comes on for a few seconds when yon turn the ignition switch ON (II). If it comes on at any other time, it indicates one of the engine's emissions control systems may have a problem. Even though you may feel no difference in your vehicle's performance, it can reduce your fuel economy and cause your vehicle to put out excessive emissions. Continued operation may cause serious damage. Taking Care of the Unexpected