Isuzu Turquoise is a coach fitted with the ISUZU 4HK1 engine, which features a DPF particle filter.
The emulator simulates a fully-functional diesel particulate filter so that the vehicle does not continuously regenerate the filter.
The indicator "DPD" on the dashboard is responsible for the exhaust aftertreatment system - more specifically for the DPF particulate filter
After repair, the exhaust system does not report any errors.
Below are pictures of the installation of the DPF emulator