MIL = P0420

Honda Civic 1997 CX Hatchback
181,000km

I got the same code a few years ago. Seems the oxygen sensor that sits 'on top'
was no longer functional. I paid for a genuine Honda replacement.

Father-in-law has generic OBD-II reader. Same code came up again a few weeks
ago. There are no other codes. I did not reset the MIL and have been driving
with it on without noticing abnormal gas consumption...

I am always afraid of bringing the car to the 'stealership', but I don't feel my
usual mechanic can properly diagnose whether it's a lazy $200 sensor or a gunked
up $600 cat...

Any thoughts, other than bringing it to Honda in & around the Montreal area?

Thanks!

 

I've been driving a 96 Camry for years with the Check Engine light on,
when they check the code it's Catalytic Converter, which was OK, it
eventually turned out to be Coolant Temperatue Switch, it was corroded
badly, all's fine now.
Bg

 

How was that tied to the P0420 code? P0420 has nothing to do with the
primary sensor.

See here for more info:
http://www.tegger.com/hondafaq/p0420.html

Did anybody try simply resetting the ECM and waiting to see if the same
code recurred?

You won't notice a thing with a P0420, but you might with a different
code.

It is an absolute certainty that a "gunked up cat" is not at all one of
your worries here.

See here for more info:
http://www.tegger.com/hondafaq/p0420.html

You'll never bring it to Honda no matter where you go. Honda Canada Inc.
does not service customer vehicles.

If you're suspicious of garages that have paid for a Honda franchise,
then you'll have to find a good independent somewhere with the same sort
of Honda-specific knowledge, information and experience the dealer has.
Good luck.

Have you asked the, uh, "stealer" if there any outstanding TSBs or HSN
articles addressing your problem? Non-franchised outlets will not likely
have access to these.

 

to emphasize your comment: "A long, hard, highway drive may cook off
enough of the contaminants that the cat may start working well enough
again to turn off the light." that is indeed true. catalysts need to
run hot to be efficient. just pottering along is not good enough. need
to take the car out for a blast every so often. it keeps the catalyst
working, burns the carbon out of the cylinders and cleans the spark
plugs too.

 

How was that tied to the P0420 code? P0420 has nothing to do with the

Thanks for the reply Tegger.

Actually, it got me thinking and it seems the last time I got P0420 was in
August 2004. It coincided with some 'rattling' noise coming from the exhaust.
The dealer's remedy was to replace two (2) exhaust 'donuts'. The car still has
the original muffler and there is no rattling that I know of...

For now, I think I will try to find some Techron (Tactrol here in Canada) and
reset the MIL. The cracked exhaust manifold warranty extension ran out about 2
years ago.

Thanks again your thoughts Tegger.

 

The dealer won't analyze it either. P0420 he will just replace the Cat. With
a good OBDII scanner you should be able to analyze the )2 sensors. For some
info read this tip http://www.troublecodes.net/articles/catfailure/