i know there is probably another post i can check out but i have a pretty specific issue.... I have a 98 honda accord with the 2.3 vtec 119xxx miles. here we go..... first off nobody can start this car but me....i have to hold the key in the start possition for a little longer then normal then it starts up. When i put the key in and turn it to accessory, sometimes the dash lights dont turn on and i have to give it just the slightest nudge twards start without turning it over then the lights kick on. When im driving it will sometimes just shut itself off....like on the highway doing 70 and it will just cut out...all the gauges will go down.. but...sometimes the gauges just go back to normal after it has seemed to shut off and it will run after that. the guys at my dads shop insist it is because i have a cold air intake on it and im positive thats not it...i figured maby i missed the mass airflow sensor and its acting up but im almost positive the mass airflow sensor is on the trottle body. i have tried many things...i had the po420 code on my cat...i replaced the front oxygen sensor and plugs and wires.. then i put a test pipe cat on it and the code was still on so i put this little spacer on the rear oxygen sensor and the code is off now...i just got back from advanced auto parts and i had my battery tested...starter tested...and altenator tested, everything is good. im wondering if it is a fuel problem because it seems like the only thing minus like the ignition or something... maby fuel filter...i figure it is not the fuel rail because the car would prob not run at all.... this is a very agravating issue...the car runs fine and gets me where i need to go but sometimes it will put out on me and ill have to re start it....ALSO ****** the issue when the car turns off seems to happen when i am turning my blinker on... like right in the middle of turning it on it will put out...many times it has happend when i turn the blinker on but most of the time like i explained earlier ...the gauges all go down and it seems to have shut off but then turns back on.....FRUSTRATING PROBLEM!!!!!! SORRY FOR SUCH A LONG POST!

 

Your problem is likely a faulty keyswitch assy. Very easy to replace. Check DIY section or search for keyswitch replacement.

Exhaust leaks ahead of catlytic converter can cause P0420, or converter is damaged. Mechanical fix works, but may not pass state emisssions inspection if they look at exhaust system.

good luck