I recently failed my smog test in my 1995 Honda Civic EX. I have 175k miles on the car and my catalytic converter needs replacing. I didnt want to spend $1000’s of dollars making all the necessary repairs so I spoke with my neighbor who messes with cars. He suggested to try the following:
- The most important thing to do before going to get smogged, is to get your engine and exhaust system hot. Drive around for 30 minutes in 4th gear to flush out extra particles.
- Replace your spark plugs. If a plug isn’t firing properly your going to have much more than just exhaust coming out.
- Replace your air filter.
- Run though one tank of gas with fuel system cleaner.
- Fill up the tank with premium gas before going to get smogged.
Some other things to try are:
- Replace the fuel filter to ensure that only gas is getting combusted.
- Get an oil change.
For me, doing steps 1-5 helped me pass my smog test. I only passed by one point, but that gets me through another 2 years before having to address this again.