2002 S80 Oxygen Sensor

[draser]

Sensor readings are fine, curious what trims will look like...

[puntmeister]

Finally got the correct sensors, and got around to replacing them.

As you suspected, the old sensors were fine. Ended up getting the same codes shortly after installing the new sensors (and deleting out all old codes).

LTFT is now about 10% for "Bank 2". Something like -3% for "Bank 1".

O2 sensors reading lean for Bank 2, rich for Bank 1.

I'm at a loss as to the cause.

Bad injectors? I've had them cleaned (on the car) and always use 91 octane.

Vacuum leak? (though, seems to me, a vacuum leak would affect all cylinders, not just one bank)

I'm thinking about taking it to a shop for diagnosis - but, not many shops are keen on just doing diagnosis, and even fewer are particularly good at it.

[draser]

I'd get readings at idle, 1500 and 3000 rpm. If the 10% starts going down then it's an air leak. I'd release some propane (or spray brake cleaner) around intake manifold and injectors (injector o-ring?) for bank 2 and look for idle change. The leak can be in the exhaust side as well, even a loose spark plug. Bad injectors - if they were clogged I'd think it would be all 6. If it's just one on bank 2 I'd think you'd get some misfire codes for the one cylinder. I'd check fuel pressure at idle as well.

[puntmeister]

Cleared everything out, ran for some time, rechecked:

Now showing LTFT +7.8% (on both). No more codes for O2 sensors.

Checked for vacuum leak - nada (both physical checking for leaks + STFT at idle/1500/3000 rpm - all = no vacuum leak).

Current codes: Catalytic Converters inefficient. This was just a matter of time.

The cat on it is a dual in/dual out - I can't find a replacement dual in/dual out which has dual rear O2 sensor ports. Is this really such a rare configuration?

The replacements I can find have a totally different design - with the cat attached to exhaust manifolds. Pricey and convoluted install.