This Peugeot 3008 with a 1.6 HDi engine was tested with a smoke meter after an earlier test had produced high readings. The vehicle still had its emissions-control components, including the particulate filter, EGR and catalytic converter.

Following diagnostics, the engine control software was adjusted and the car was tested repeatedly with the measuring instrument. The video shows lower readings in the later tests than at the start. The units are not specified, so these figures should not be compared with a regulatory limit without additional information.

A smoke test is one way to assess diesel exhaust, but it does not replace a full diagnosis. If a vehicle exceeds the permitted smoke level or a petrol engine has high CO readings, the cause should be identified before choosing any repair or calibration work.