How to track down an exhaust leak?

zax1stgxb · 10-01-2009, 10:12 AM

my check engine light is on, so i went to auto zone to see if they could tell me what the problem was. it came up with a P0420 code, which they told me was an exhaust leak. actual definition:

1.)air leak in exhaust before rear O2 sensor.
2.)AF sensor error
3.)fuel system fault
4.)faulty catalytic converter

i figured that i could prob eliminate 3 & 4 cuz its running fine.

any help would be great......

PCH · 10-01-2009, 11:34 AM

Usually it's the Cat that causes P0420. Warranty?

zax1stgxb · 10-01-2009, 11:40 AM

no......

i bought it used.

PCH · 10-01-2009, 11:54 AM

Federal Emissions Warranty on the Cat is 8 years/ 80K Miles. If you are within that, try having the Toyota take care of the Cat replacement. More info here regarding you not being the original owner: Information on Manufacturers emissions Warranties for 1995 Newer Cars and Trucks | On-Board Diagnostics (OBD) | US EPA

zax1stgxb · 10-01-2009, 12:19 PM

i only got 45k on my car, so hopefully ill be able to take it to the dealership and they can fix it for me.

dood, thanks for your help! is there anything about cars that you guys dont know.....?

PCH · 10-01-2009, 01:19 PM

If it ends up being a Cat hope they cover it, the factory part is about $1K. You would hear an exhaust leak if it had one. O2 sensor can sometimes throw the code you have, but most likely it's because of the converter. Fairly common code on xB's BTW.

zax1stgxb · 10-01-2009, 01:24 PM

$1K? psssshhhh! is that all?

i mean i can sorta hear a leak, but i got under there last night to see what i could find, and there were no hole or anything anywhere! everthing looked really good. my o2 sensor wasnt loose or anything. so i tried to find the place that i thought the leak was coming from, and i finally figured out that there was a big 2" hole right @ the tip! lolz!!!!

but for realz its in real good shape!

PCH · 10-01-2009, 01:47 PM

Found some nice info on the P0420. A little mind bending but throwing it in for reference: http://www.myjdmphoenix.com/images/0...efficiency.pdf

zax1stgxb · 10-01-2009, 01:56 PM

well i certainly would like to thank you for your additional research on this, but i fear things have taken a turn for the worst....

as i was reading that last article, somewhere around page 2 or so, it seems that i have gone cross-eyed. due to this unfortunate sate, i was not able to finish reading the entire thing.

now my engine light is on AND i have to see a doctor....

once again, thank you.

thefonz · 10-03-2009, 01:20 AM

like pch said. needs a cat. take it in soon. might plug up and your car wont run at all.

zax1stgxb · 10-13-2009, 07:37 AM

let me give you just a little bit more back story about this check engine light.
about 4 months ago, i filled up my tank at a BP station. as i was leaving everything seemed fine, then bout a mile or so down the raod my car would barely move.
so i limp my car to the side of the road, and have no idea what is going on. but when i was getting gas i remembered that there was a dood that said he was changing the filters on the pumps. that was the only lead i had, so i drove the mile back to the station. (not a pleasent mile, because my car would barely go over 10 M.P.H.)
after all was said and done, i ended up getting mostly water in my tank instead of gas. the mechanic that fixed it said it was about 70% water.
i only drove about a mile like that, but i was wondering if that could have messed up my o2 sensor or some other part of my exhaust.
the engine light has been on from the time of this incident. when i asked my mechanic about it, he said that it was just a drip or 2 of water that causes a misfire every now and then. he told me to run through a tank of gas or too and see if it continues. ive been through like 20 tanks since then and i still have the light.

any thoughts.......

PCH · 10-13-2009, 01:19 PM

Water and gasoline don't mix. It takes a minute for them to separate, so water will collect at the bottom of the tank. Need to make sure your mechanic got everything out.
I'd expect for gas/water mix throw engine misfire codes first. Try clearing the ECM memory with scanner/reader and the see what code comes back first.

zax1stgxb · 10-13-2009, 02:03 PM

i have reset it about 4 times now, and the code i get now is the exhaust leak code.

do you think they are related?

PCH · 10-13-2009, 02:23 PM

Try warranty. No reason to start spending $$ on oxygen sensor or cat if you can get it done for free.

awinter · 10-13-2009, 11:35 PM

You could also Seafoam your intake system. The large amount of white smoke usually produced during this procedure should definitely aid you in detecting if you have a leak. Follow the directions on the bottle and have a friend rev your engine. While your friend is doing this, visually inspect your car, in the engine bay and underneath along your exhaust piping. If you see smoke coming from a location it shouldn't, then that's where your leak is. If you don't see smoke anywhere except out the tailpipe, then you don't have a leak.