my 2000 civic EX died on my way to work the other day, it died in front of pep boy's. they checked it said it needed a tune up, plugs, wires, cap, rotor, fuel filter, ok, the car ran ok but the next day the check engine lite came on, i tried checking the code my self, the lite flashed 76, took it to autozone the tester read PO420, i checked the tune up and did a compression test and everything seems ok. i recently put a muffler on and the inside looks sooty, i thought the plugs looked a little sooty around the edges to. i need help please!

 

code 420 is for o2 sensor ----i would clear the code wait to see if comes back ----if it does come back on --then do something about it

 

420 for oxygen lol

 

well i cleared the code and hooked up a vacuum gauge and a voltmeter to the front oxygen sensor plug, the vacuum test came out ok, didn't look like any restrictions in exhaust system, but i didn't see any voltage comming from the o/s, i let it idle a long time, so i shut it off thinking i had a bad o/s, but when i went to unhook the meter i saw that the pin i had in the plug came out aways so i pushed it in and started the car again and i seemed to be getting reading of about .2 to .78, shut it off, let it cool, took it for a ride, drove about 6 miles the CEL came on. got home checked code, it flashed #67 [PO420], could i have a bad front o/s.please help.

 

well i cleared the code and hooked up a vacuum gauge and a voltmeter to the front oxygen sensor plug, the vacuum test came out ok, didn't look like any restrictions in exhaust system, but i didn't see any voltage comming from the o/s, i let it idle a long time, so i shut it off thinking i had a bad o/s, but when i went to unhook the meter i saw that the pin i had in the plug came out aways so i pushed it in and started the car again and i seemed to be getting reading of about .2 to .78, shut it off, let it cool, took it for a ride, drove about 6 miles the CEL came on. got home checked code, it flashed #67 [PO420], could i have a bad front o/s.please help.

 

ummm --theres no vacuum ports on an o2 sensor ---you sure your testing the right part?

+ on an '00 theres 2 ox sensors -- 1 in front of the cat --1 in the rear of the cat
ya sort of have to test both to see which is working-- or not

 

i hooked the vacuum gauge to the intake manifold to see if the converter was ok.

 

im hopeing i solved it,i recently put an autozone muffler on and im wondering if they sold me the right muffler. when i put it on i noticed that the pipe coming out the back of the new muffler was about an 1 1/4" where as the pipe coming out the back of the old muffler was about 1 1/2" the same size as the rest of the exhaust.also the pipe comming out the back did'nt seem as long, all the rest looked the same, and bolted right up. so today i unbolted the muffler, cleared the CEL and took it for a ride of about 10 miles and the CEL did'nt come on, im hopeing it's just the wrong muffler, i was looking for the receit but i think i tossed it. i got it at autozone , do you think they'll do anything about it.

 

ok i solved the problem, autozone sold me a canadian muffler