I recently changed the ignition coil on my 99 Civic EX 4-door. (Found solution here) Shortly thereafter, the yellow CEL came on regarding emissions. I picked up an aftermarket coil from Auto Zone. Does changing out the coil affect the emissions in any way causing the light to go on? Tried the gas cap procedure and light will not go out. What are my options short of taking it to the deealer?

 

My gas consumption has also gone up dramatically. What is the Dilly-o?

 

Take it to autozone, get them to check the code..


My guess would be that one of your O2 sensors has failed...

 

Another thing could be the fuel filter. Also the charcoal cannister under the hood could be gone to shizzza.

 

Got a 0420 code Bank 1. changed out Primary o2 sensor. Reset light. Light came back on after a day. Ever since I put in that new coil, the idle has been off a little. Every now and then the idle drops to almost zero and feels like it wants to cut out. The exhaust also smells like the car is running rich. What is going on??