This is off a Volvo 2011 3.2. Inline 6 cyclinder with catalytic out of exhaust manifold. Have you guys heard of post oxygen sensor suppose to read like pre oxygen sensors? Instead of a steady signal, mine goes up and down but not the same as pre sensors. I looked at my catalytic and it's clean like no carbon deposit! My issue is I am trying to get my sensors monitor ready, all 4 are new because the old ones are lazy. Any thoughts? I have a innova scanner so I don't have a graphing device yet
Without graphs it is difficult to help with the diagnosis as a picture paints 1000 words. Even the cheapest eBay Bluetooth OBD2 dongle will give you graphs on an android device.
When hot and at steady idle are the upstream sensor votlages switching hi-lo-hi-lo about once second ?
In the same conditions what are the the downstream sensors doing? What max and min voltages are they showing? Are they going fully rich when hit the throttle ? Then fully lean for while when lift off?
Is a P0420 or P0421 or any other P042x series codes getting set ? No misfire codes?
I with the upstream sensor(s) showing a normal hi-lo-hi-lo I have never seen a P0420 or P0421 code and downstream sensors working where the catalyst wasn't history.
" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)
Last edit: 9 years 4 months ago by Andy.MacFadyen.
