Some 2015-2018 Transit vehicles equipped with a 3.2L diesel engine may exhibit "Drive To Clean" maintenance messages and/or an illuminated malfunction indicator lamp (MIL) on with DTC P2459, P2463, and/or P246C. Vehicles may also exhibit frequent automatic exhaust regeneration attempts. This may be due to vehicles being used in a stationary or off-highway, low speed applications. If automatic regeneration attempts are unsuccessful, these symptoms may be a result of soot accumulation in the diesel particulate filter (DPF). These vehicles may benefit from operator commanded regeneration (OCR) capability so complete regeneration cycles may be performed in a stationary setting. Follow the Service Procedure steps to correct the condition.