Re: 1996 bmw 318ti...engine code 420???

I had the same problem with my m44 engine, but it occured at 110,000
miles. I went down to the local checker auto parts (CSK), and asked the
clerk about it and he thought it was was more than likely the oxygen
sensors. by replacing both O2 sensors the problem went away until a rock
hit the front one and broke it off. I would assume that the same problem
exists on yours. Usually O2 sensors are really stuck in there so get a
toarch and get them red hot they come out really easy then.When putting
the new ones in use some of the sensor safe anti-seize, but be sure to
only get it on the threads and not the sensor. Also do not touch the
sensor part, the oils and salt on you fingers will dramatically shorten
the life of the sensor. The comment in this thread about the O2 sensors
costing about $75 and $100 is resonable, the best price I found for these
was at www.bavauto.com. The biggest problem with the cat is that a lot of
places still use the higher sulpher gasoline which is the main thing that
clogs cats now. If you are in Minnesota or Wisconsin I would suggest using
the holiday blue planet gas, it is complient with the new nation wide fuel
standards that will take effect in 2007 for low sulpher, if not wait 6
months.

On Sun, 05 Feb 2006 13:39:32 -0500, 19831993ranger wrote:

i have this code 420 from my scanner obd-11. catalyst system efficiency
below threshold bank-1

anyone know what that means...maybe my cat is bad??????...hope not$$$$$.
.

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