O2 sensor (& fault codes)

[distendo]

When sorting out a flat battery (tailgate light on 48hrs :doh: ) this AA guy OBD2 checked out the engine warning light: code p0171, which is bank 1 system too lean. He checked the O2 sensor, which was flatlining, and said it should show some changes as the revs changed. Sooo... before I head off down Pye Volvo (B'ham) I thought I'd see what I can do, like check the connections to the sensor, but Haynes isn't too clear on where it is. I scanned in the pics: anyone care to identify what I'm looking for? And how many wires come out of a '98 V70T5 o2 sensor anyway?

The little rubber elbow tube under the manifold was leaking when I got the car, but Pye picked it up and sorted that in a service. I can't see any sign that being knackered, and surely that wouldn't stop the O2 sensor from reading out ok...

BTW, I've been looking for fault code info, and know about these two look-up sites, but does anyone know a better source of code info?

http://www.actron.com/code_lookup.php
http://www.obd-codes.com/

Thanks!

[distendo]

Ohhh-kay... not a nibble, eh?
I understand the 02 sensors are very important for the mpg & mph etc.

I've just bought an OBD2 interface & software with USB to laptop connection which seems to work well (esp. for the price) on my '98 V70 T5. See http://www.gendan.co.uk/ and http://www.enginecheck.co.uk/ but check out Gendan's shop on Ebay (search on 'sitereams').

It shows both 02 sensors fluctuating, which ain't necessarily good news, after I read some stuff on what looks to me like a great source of diagnostic info at:
http://www.aa1car.com/

But I still don't know whether the 02 sensors on my machine are 2, 3 or 4 wire versions. I suppose I'm going to have to look underneath (moan, whine...).