FlyingVFR

Hi. Having problems with my daughters 2012 forester diesel - it's not trying to regenerate. No garage has been able to identify the problem despite spending many hundreds of UK£. These garages either wanted to remap or clean ( it's been cleaned many times) so a different agenda!! Hence I need to fault find myself. Does anyone know what the DPF sensors are left to right ( its RHD) please?