Land Rover Repair: 97 Disc I O2-Sensor Code & Evap Purge Valve, emission testing center, o2 sensors

Question
Readings from Emission testing center OBDII

P0441   Evap. Purge Valve Incorrect Flow Fault
P1191   Oxygen Sensor Heater Circuit Open Downstream
P1193   Oxygen Sensor Heater Circuit Open Downstream
P1194   Oxygen Sensor Heater High Resistance Downstream

I've recently found out that this model has four O2 sensors (dealers $432 each/www.oxygensensors.com $109 each from your site). I'm hoping to only replace one. I was wondering where is this O2 sensor located according to the fault code, is it after the catalytic(Post-Cat)?

Am I going to have to replace Evap. Purge Valve?

thanks in advance.

Answer
You've got faults for two of your four o2 sensors, and the faults may indicate bad sensors or wiring issues.  The purge fault may point to a number of things.  At our shop, we'd follow up with a smoke test and a test of the purging with the Land Rover T4 tester to determine exactly what repairs are needed.

Your codes give you some information but not the whole answer.  More tests are needed.