OBD II Codes

[hibshman25]

My check engine light came on in my 328i so i took the car to auto zone to get the codes. The following three codes came up: 455, 430, 420. I've been told 430 and 420 are oxygen sensors, and the 455 is a gross evap leak. my question is which o2 sensors. before or after the cat? i checked my gas cap concerning the evap leak, but didn't find anything. anything else obvious to look for? thanks in advance for any help.

 

[pcy]

Re: gross evap leak
Gas filler cap's gasket is probably worn out. Get a new cap (it's about $10,
if I remember correctly when I had to buy 6 months ago).

I had the exact same error; after replacing the gas cap, that error is gone.

Good Luck

 

[Looky]

Hi,
my software said...

Fault Code 420 -> catalyst system below limit value (bank 1)
Fault Code 430 -> catalyst system below limit value (bank 2)
Fault Code 450 -> vaporization issue control system (big leakage)

hope it helps
Looky