0420
#2
RE: 0420
[align=center]Hi Brian,[/align][align=center]It sounds like it could be a bad 02 sensor.[/align][align=center]Iwould reset your computer, and see if it returns, and if it[/align][align=center]does, I would have your sensors checked.[/align][align=center][/align][align=center]I hope that one of our experts tech members reads your post,[/align][align=center]and give you other possible solutions to your problem.[/align][align=center]Good Luck from[/align][align=center]`Space[/align][align=center][/align][align=center]Is you Monte Carlo smoking anything illegal ? and throwing the code 420 ?lol[/align]
#4
RE: 0420
Brian, the way I reset mine in my 05/06 Monte was to disconnect
the negative battery post for about 5 minutes,
and then reconnect. If your code re-appears,
I would thencheck out your 02 sensors.
I am not a tech, and just posting what I have done and have
read by others on the MCF.
I would wait for one of our more experience members to confirm
the above. But, if no one responds, then give my solultion
a try.
You can`t hurt anything by disconnecting your battery, except
to reprogram your stored settings.
Good Luck, from `Space
#8
RE: 0420
dustybird3 is right. Some aftermarket replacement cats just do not operate at the efficiency level that the software calibration in your Monte Carlo's powertrain control module expects. When I replace cats on my customers vehicles I only use OEM cats. Its one of the cases where the saying "you get what you pay for" really applies. What type of cat was installed on your Monte??