1991 honda civic faild emission test no check engine light on.?

find the on ramp for a highway, put the gas pedal to the floor while getting on the highway. Do this a couple of times. This is known as blowing the cobwebs out. It helps clean the engine and exhaust of carbon

Also, next time, drive your car for at least a half hour before you show up

But your problem could be linked to the above or dirty injectors, poor tune/dirty air filter and more

there's a distinction between the verify engine gentle and the upkeep gentle. i think of the single which you’re talking approximately is the upkeep gentle. to coach this off you may have the key contained in the off place, carry the odometer reset button and turn the key to the on place mutually as nevertheless preserving the reset button, proceed preserving till the gentle is going out. turn the key to the off place and then try turning the vehicle back directly to verify if it worked. the truly verify engine gentle potential that the vehicles workstation has got here upon some thing incorrect with the vehicle. it extremely is a sort of issues from the gasoline cap not being tight adequate to a minimum of a few thing important. in case you be attentive to that it replaced into some thing small and you opt for to reset it bypass under the hood and locate the fuse container it truly is located via the battery and do away with the fuse for the eu for about 30 sec and then reinstall it. that would reset the eu. previously you do this i might attempt to verify what the priority is. In my case it replaced into basically a lose gasoline cap and after tightening it, the gentle in no way went off. So I got rid of the fuse for 30 sec and the gentle has not come back on when you consider that. desire this facilitates.

needs a tune up

or what really helps me pass all these tests is

warming up the car

running the gas to 1/4th a tank

then put 1 gallon of denatured alcohol (home depot, lowes)

then take it to the smog shop (with it warmed up of course)

and if there is a line don't turn off the car leave it running

also after the smog you want to fill up the tank to dilute the denatured alcohol or run it empty because it can erode the fuel lines

this helps with smog because its such a high octane that it burns cleaner

i've done this twice with 2 different cars and i've always passed with flying colors.

don't be scared to try this i highly reccomend doing it!

It's out of tune, or the catalytic converter is shot.

If you need a converter shop price with your local phone book "muffler shops".

Maybe you can get a cheap generic...