02 Sensors 4.0 Discovery2 Running on LPG

i have the following error codes po134 O2 sensor,po129 Barometric Pressure too low,po135 O2 sensor bank 1,po155 o2 sensor -My lpg man tells me these faults need fixing before he can attend to the gas system,my mechanic says some off these may be due to running on lpg so i'm a bit stuck between the two (both nice guys)but i'm stuck -they all not going to be faulty at once.I've tried running just on petrol and i seem to get the codes coming up after they have been whipped so is the lpg playing any part really? Can anyone help please cheers

Heavy running on LPG will over time cause the ecu to fault as it cannot adpt due to the LPG being incorrectly set up and running over lean
Do you have pre and post lambda sensors?
Have you done live data reading on all the sensors on petrol what are the longhand short furl trims at?

Thanks i understood that running on LPG can result in Lambda sensor problems -I'm affaid i'm way behingd you on fuel trims etc (althrough the gas guy did comment that as a result fuel trims were not being made)but a local LR specialist is due to take a look at this for me as my local mechanic was not confident of progressing with the information provided above from the snap-on reader.Thanks for your notes. I would also therefore expect a better economy once this is sorted.
Regards and thanks once again.

Snapon is a limited code reader you need a better live data to see what the sensors are doing and switching at

cheers -upstream o2 sensors now replaced ,now suspect faulty wiring on common feed to o2 sensors (Being looked at by Northeast Land Rover) but power detected at junction box when not at sensor so may now be plain sailing with a new feed wire run in its place..

proved to be nothing of the sort and new/replacement ecu required -good service from northeast LR again but more expense