Bit late if going in tomorrow but are you sure it has been doing a regen of the DPF. On my Greenline the exhaust note takes a deeper note when doing a regen but does not indicate anything on the instruments. Had an issue a few years ago of not re-gening during the colder months due to a thermostat stuck open so never getting to required temp to initiate a regen. Lack of temp gauge (only blue light that extinguishes at around 45 deg.C), only identified by running Torque app on phone via a bluetooth OBD adaptor. DPF clean can be done yia an aerosol spray down the larger of the 2 pipes on the differential pressure switch accessible top rear of engine on drivers side. Theory - increased back pressure from blocked DPF would stop flowing as much exhaust gas reducing boost. Where the below says Vacuum this changes to boost pressure in psi generally showing around 18psi at full boost.

Edited 18 June, 20241 yr by KeithCheetham

The noise for this is quite a high pitched whoosh.

Took it to the second garage today. They're pretty sure it's the EGR Cooler. They think either a gasket or a seal has gone. Should be sorted tomorrow. EGR Cooler makes a lot more sense than DPF.

 

Not too bad I suppose. Believe it or not, I'd purchased a new jack and intended on getting up behind the engine to see what was going on where the EGR cooler sits. I doubt I'd have been able to visibly see the leak but maybe....

 

Oh well. Might be a cheap fix after all. Glad I didn't stick with the other garage.