freemee22

Hi, I got a honda civic 99 dx from a friend of mine. She had the car tune up by a dealership and after 3 days the check engine light came on. I used a code reader and it came up as "P0420" Catalyst System Efficiency below threshold (bank 1), I thought that the mechanic has done something to have the CEL to come on after 3 days so I erase it using the code reader and she went ahead and have the car smog checked and it pass with flying colors , now I got the car after 5 days the CEL came on again and it reads the sam "P0420".

Question is am I going to get a more specific code if I use the service check connector in the car and count the flashes on the CEL? or am I going to get the same code as the code reader? I read somewhere that P0420 means the catalytic converter is bad, but if it is bad, it shouldn't have pass smog or will it pass still with a bad catalytic converter? will a bad O2 sensor give me this code?

any help or suggestion as to how to trouble shoot this problem is greatly appreciated.

BTW the car is running good and fuel efficiency is still the same.

thanks

Chiovnidca

Needs a new cat, it's not passing the ECUs check routine.

freemee22

if it needs a new cat then why did it pass the smog check with flying colors?

thanks

freemee22

I just check the connection going to the O2 sensor both primary and secondary and the primnary have about 12 volts on the heater lead but on the secondary it doesn' have any voltage. This is with the ignition on and the car is cold didn't even try to run it.

Does both heater lead that comes from the PCM have to have 12 volts or is it just the primary?

thanks


Modified by freemee22 at 11:32 AM 6/4/2005