Ok been trying to figure out whats causing this code.A month ago i scraped my exhaust on a drive pulling in.I'm to low and the drive is to high.
But it scraped and caused a p0420 immediately,so i thought i may have crushed my rear o2 senser,well repalced that,and it still threw a code.
Then i went ahead and replaced the front,it had about 30k on it, so it was getting time,and it still is throwing a code.
I just within a few months ago put a new exhaust on the car, 2.25 from the cat back with resonator and a borla muffler,i made a post about it.
So the cat is a brand new magnaflow cat,and yet I'm still getting this code,i did some search,but all that mentions is either bad o2 or cat,and it shouldn't be either on mine since there brand new parts.i have checked for leaks at the manifold and flex pipe(still running stock manifold) but i cant hear or see/feel anything.
So my question is,what else can cause a p0420 code?I think that when i scraped the exhaust it may of ripped the flex pipe and causing a leak,cause the cat wasnt damaged or the exhaust wasnt bent.So i'm looking for ideas.
Did you clear the code? or are you waiting on the light to turn itself off? It'l take a while (like three or four "full" ignition cycles to clear itself) When I say "full" i mean all obd2 checks are completed. Also check your wiring to the back o2 sensor, if you have a scope or a graphing scanner watch the pattern of the rear o2 sensor versus the front one.
Your WHAT hurts?
Yeah i been clearing them immediately with my scan gauge 2,so i haven't waited till it turned it self off. The wiring looked good,couldn't find anything wrong anywhere visually .
I don't have access to a scope or scanner,i may look into that more,cause i cant find anything else wrong,but is there anything else that can cause the 420 code besides the cat and o2 sensors?
What brand O2 sensors did you buy when you replaced them?
from what i have seen on hyundai and vw a p0420 with out any other codes is always cadillac converter went bad but not sure if its same with cavs
Sig thanks to bxmobkrazey on gmscf.com
yes thats usually the oh snap time to replace my cat now code
anybody you know have a scanner (read modis) so you can see what the rear sensor is doing? and what brand sensor did you get and what kind ( direct fit or splice together)
I'm using Bosch oem style o2 sensors,both front and back.I called big o tires and they have the ability to scan my car while running so if i get a chance i may run up there Saturday to have it checked.
I'm gonna be mad if the cat is already dead,its brand spanking new.
Neeed to see what the 2 O2 sensor are reading.
FU Tuning
i would check your cat. i had the same problem when i had my exhaust put on 6 months ago. the CEL came on and come to find out the Magnaflow cat the shop put on was to small for my Cavy.
Do you have hpt? And do you have emissions inspections in your state? I have seen extremely High flow cats cause a 420 prob. In fact I just disabled the codes in my k1500. I know cats are working, just they are a little modified to flow better.
Your WHAT hurts?
CAV2HAV wrote:i would check your cat. i had the same problem when i had my exhaust put on 6 months ago. the CEL came on and come to find out the Magnaflow cat the shop put on was to small for my Cavy.
Funny you mentioned that,cause after i had my exhaust done,the guy who installed it told me the cat may trip my cel cause he thought it was to small.
But i had it on my car a month before i scraped the exhaust and it never gave me any problems.So now i'm confused.
No i don't have access to hpt i wish i did tho,then i would really like to turbo my car.
well now that i posted that my CEL just came on for the second time in 2 weeks on my way home today. will be getting it checked out tmrw at work. im goin to leave it on til my mom can have one of her techs at the chevy dealership she works at can look at it.
yeah keep me posted.
So have you changed your cat to a bigger one?
its the right size cat, but im thnking it could be the 02 sensors, cause my cavy just rolled over 50000 miles the other day.
I know this doesn't help much but:
I've had that 420 code on my car for about 10 months. I would clear the code about every other month, but it would always come back on. I replaced my primary O2 sensor with a no name brand one two weeks ago and everything is fine now. No more codes. I am running an aftermarket header with magnaflow cat 2.5" pipes.
From what I've gathered and my experience, it's no big deal to run around with the engine light on as long as you check it periodically. I am glad the light is off now though. Crossing my fingers.
Well mine turned on again today,it been a few days since it last turned on.
I going to get it scanned today or tomorrow.I think I'll leave the light on this time.
mine is a Catalytic efficiancy code. took it by the exhaust shop and they spotted a leak. goin by today to get it welded up. if that isn't the problem then the cat has gone bad. i was told by a tech that my mom works with that running Premium will cause an aftermarket cat to go bad. luckily my cat is only 6 months old and under warranty.
There is a scanner that can test each individual O2 sensor and give you live readings. My friend has a MAC Tools one. Very useful tool. It even tells you what to do to trip each individual code. So when you clear it you can do the step by step process and see for sure if it is your O2 sensor. Live reading can give you and indication too, if you know how to read them... Unfortunatly I don't, but when he scanned my car he said that he could tell my O2s were fine by the voltage readings on the scanner.
Look for someone with these scanners, they are expensive but great for problems like this. I think he said retail on it was $4000 CAN
took my cavy to the exhaust shop yesterday and they found a small leak in the pipe before the cat. they re welded the seems and cleared to code. if the CEL comes back on then it is the Cat that is bad. the shop will order me another cat if bad since its under warranty
CAV2HAV wrote:took my cavy to the exhaust shop yesterday and they found a small leak in the pipe before the cat. they re welded the seems and cleared to code. if the CEL comes back on then it is the Cat that is bad. the shop will order me another cat if bad since its under warranty
See i was wondering if that's not mine problem,i cant see the flex pipe,but i wonder if it doesn't have a hole in it causing my code.
i would put it on a lift and check it out. even a small leak can throw the code. mine was on top of the pipe.
I going to try looking into it this weekend.
well its back on and i am dropping her off at the exhaust shop tmrw. they are gonna swap out the Cats.
Man, hey what brand cat do you have on it now?
