need help with air/fuel mixture problems - 986 Forum - The Community for Porsche Boxster & Cayman Owners

bwdz · 08-20-2017, 06:09 PM

I'm surprised you don't get the old P0420 code with the secondary reading basically nothing. Supposedly the secondaries don't affect the air/fuel but I am speculating that they do in the long term if it sees something it doesn't like for extended periods of time. You should be steadier on the second 02 and closer to .5v but it should still bounce around the .4 to .65 range.

CrisZenithBlue · 08-20-2017, 06:46 PM

Quote:

Originally Posted by bwdz

I'm surprised you don't get the old P0420 code with the secondary reading basically nothing. Supposedly the secondaries don't affect the air/fuel but I am speculating that they do in the long term if it sees something it doesn't like for extended periods of time. You should be steadier on the second 02 and closer to .5v but it should still bounce around the .4 to .65 range.

it doesnt move at all so that means its busted right?

bwdz · 08-21-2017, 05:17 AM

[QUOTE=CrisZenithBlue;547491]it doesnt move at all so that means its busted right?[/QUOTE
Either the o2 is busted or wiring to it or the plug etc... You have to go drive the car and get the cat and o2 nice and warm to get accurate readings. They wander around when cold startup and then smooth out but your seems to be dead. The smoke test is great at finding vacuum leaks but you have to stick it in several places, I even throw them in the dipstick on cars to look for PCV problems on vehicles or other gasket leaks by just slightly pressurizing and filling the crankcase.

CrisZenithBlue · 08-24-2017, 06:35 PM

Quote:

Originally Posted by bwdz

I'm surprised you don't get the old P0420 code with the secondary reading basically nothing. Supposedly the secondaries don't affect the air/fuel but I am speculating that they do in the long term if it sees something it doesn't like for extended periods of time. You should be steadier on the second 02 and closer to .5v but it should still bounce around the .4 to .65 range.

now that i think about it.. a few months ago i got the P0420 code, i reset and it never came back so i assumed the cat is fine. i never checked the O2 sensor though.