2000 V70XC ECM-4801 Three-Way Cat Convert efficiency, bank 1

[carboncow]

Helping a buddy trouble shoot with the vida dice. I seem to recall 02 sensor goose chasing on a similar code on my 01 and/or 03 but wanted to start a new thread in his world of 2000.

ECM-4801 Three-way catalytic converter (TWC) efficiency, bank 1 -

I've seen mention of injectors, cats and 02 sensors...I recall talking with people before that the down stream sensor being out of spec and trigger the upstream (bank 1?) or maybe just replace the upstream. Yes, no, maybe...

How does one go about troubleshooting this...as it seems many in the past just throw money at the main variables till they figure it out...no thanks!

EDIT: I should add he has no drivability issues everything seems happy to him in this newly aquired 180K mile ride.

[Matty Moo]

I had a reoccurring 0014 code that went away on its own and then turned into that code. Retimed it 110% properly the second time and it was gone.

For some reason I always have a hard time with the vvt cars when t-belt swapping.

[carboncow]

I'm not sure I understand 110% timing...how do you time these electronic vehicles...I know nothing to adjust. Is there something with these older ones and the VVT then can be adjusted?

FYI there were no other codes present (as you can see).

[Matty Moo]

I mean getting it exactly perfect.

I can do a t-belt on a non-vvt car quickly and with zero problems ever. Vvt... I do it exactly how you're supposed to and get codes afterward every time. Go back and do it again and then it's set. It's almost as if some forces in the universe are working against me.

But, if that's the only code that is there then of course that isn't the problem. What you have points to the downstream sensor.

[carboncow]

Thanks.

Downstream is Bank1...or does a bad downstream trigger Bank1?

I recall talking to Jimmy about this before and getting really confused!

[jimmy57]

OBD is the confusing part. "bank1" is the only bank on that car. On some of the 6 cylinders they split the exhaust and have separate cats, at least light-off cats, for 1-2-3 and 4-5-6. With that arrangement there are two "banks".
Your code is the result of the rear O2 sensor not being stable in the .65 to .75 volt range when the catalyst is warmed up and the engine load is stable. Front sensor will oscillate within an acceptable range and the rear will get pretty stable when catalysts are good. When catalyst is not doing well the rear will not be in the range mentioned or even oscillate more or less synchronously with the front sensor. The catalytic reaction uses stored oxygen in substrate and the reaction leaves the output with little oxygen. .65 to .75 V is the reading of a binary sensor with very low oxygen level in gases.

A high miler car (150K and up) is suspect for a worn out cat. Faulty sensor (usually front) can also be a cause. Sensors can be evaluated with a good level of trust by watching readings on scan tool for front if wideband sensor (99 up Volvos) and either scan tool or direct for rear. Engine at normal op temp, create a vacuum leak 1/8 inch hole size or a bit larger. Watch the scan tool when the leak is created. The oxygen sensor should respond to lean (wideband lambda value >1, binary voltage < 0.5V) within 2 seconds. After the leak is present for 2-3 minutes then plug leak and watch for rich indication (wideband Lambda <1, binary voltage > 0.5V).

[kahl]

HI Jimmy, How do you know that this car's rear O2 Spenser is unstable in the .65 to .75 voltage range? I am trying to understand Shawn's screen shot. I do not see anything relating to voltage.

[carboncow]

Jimmy, I knew you would pop in...thanks.

Maybe I can get him back over and hook up Dice again and do a live reading with tests like you said...and share that data...or do you agree with Mattie Moo that it's most likely the downstream sensor.

Kahl, what I shared only shared are codes. One of the tabs shows a snap shot of values at the last failure...and you can also select live data values for many sensors at once too...which we may do next.

[kahl]

Just let him know when you are available. I bet he has more treat for a certain lab. Notice I did not say a chunky yellow lab.