You could try the guys at ECU Tech. I can't vouch for them personally or by virtue of this forum, but I am a member of their own forum and they seem to be well versed in Citroen BSI & ECU repairs and coding to component level. Have a look here and get in touch to see if they can help you.
https://ecutech.info/our-services/
https://ecutech.info/our-services/
______________________
Current:
Not a Citroen!
______________________
Previous:
2017 B9 1.6 BlueHDi Van
2012 B9 1.6 HDi Van
2008 M59 1.6 HDi Van
2003 M59 1.9D Van
Current:
Not a Citroen!
______________________
Previous:
2017 B9 1.6 BlueHDi Van
2012 B9 1.6 HDi Van
2008 M59 1.6 HDi Van
2003 M59 1.9D Van