1998 C70 Couple, 210k.

I suspected it was coming. Saw this code pending a couple of times but it never set until Friday. It is the "slow" response from O2 Sensor Bank 1, Sensor 1 code. I read a fair bit about it on the BB and Matthews Volvo Site. The
problem is likely the front O2 sensor (about $100), maybe some frayed wires (if I am lucky) or a vacuum leak.

Back when my car threw a 0442 leak code, I ordered the replacement "J" hose and another "L" shaped one. The J hose fixed the 0442 error. The old J hose was split and leaking from two separate cracks. I did not end up installing the L hose because I didn't know where it went (somewhere up front) and it didn't seem to be needed to fix the CEL.

So... I'm wondering if the "L" hose is part of the vacuum sensor arrangement upstream of the forward 02 sensor. If so, could this lead to an 0133 error by making the forward O2 read incorrectly and allowing a "build-up" of deposits on sensor itself?

I'm still only slightly familiar with the B5234 engine. Can anybody point me to where this hose goes?

If this hose wouldn't be causing the vacuum leak and O2 problem, what should I be checking next?

The 02 sensor is also the *final* sensor system that has failed to "set" since the computer was last reset.