Error messages

[Sharrenred]

Hi, I have a Ford Transit Connect 65 plate. Bought January 2023 2nd hand. Consistently has error message on dashboard - 'Engine Service Now' followed by 'oul change required'. I can turn messages off but they reappear every 7 days. Van has been into Ford's multiple times and they don't know what to do. Doesn't need service nor does it need oil. They have now advised to take it to diesel engine repair however the start of my journey with this van began at a diesel engine repair and they couldn't find any fault so I'm going round in circles.
History - when I first bought van and had initial service garage found loose screws in the sump causing blockage. Fixed that. Had also had DPF removed and been remapped. Have had new DPF filter fitted. Van runs fine apart feom errors.
In process of selling my business including van and don't want to sell to new owners with the error messages.
Thank you for any suggestions

[metalworker0]

search the transit custom forum here, there is a lot of discussion on what you are talking about.
no real conclusion - but if you search a bit more than what i have, you may find a solution.

all the best.mark

[Sharrenred]

Thanks Mark, I've read everything I can about this error and can't find an answer. It's been in and out of Fords now and they don't know either. They just keep resettinjg it but it comes back on after 7 days. Just in process of selling van and think not being able to clear the error could hinder sale.