not sure what you mean about the egr valve part, is it fitted but not working/wired up or has it had something modified we don't know about.

I know on the Z12XE that a 02 model is on the change over year if they have egr valves or not as i've fitted a later engine to a Y reg Corsa and that hadn't got an egr valve so needed to change ecu.

Am i correct in thinking that a P0170 fuelling error but not actually meaning its lean or rich, my point being are we looking for a lean condition but its not.

Have you ever posted up the emission readings and any live data such as fuel trim readings and eobd freeze frame data as this may help us/you.

Alot of replies to read through,