Atego Fault code 4345

Hi, new to this lark and hope someone can help me! I have a brace of Atego 815's, one of which has had all sorts of problems. I have just had the engine ECU repaired, but the engine won't rev above 1500rpm, and there's a fault code 4345 displayed.

I've got to that dreaded stage where I've spent too much on it to scrap it, but not enough to make it work, and it seems that it might never!

Any sensible suggestions welcome. Failing that, any stupid suggestions might bring some sunshine into my life!

Thanks all....