A Parked Regen is a common term now since emissions went to the next reduction level mandated by the environmental protection agency in 2007. The emission controlled diesel engine is consuming used exhaust gases back into the intake that’s re-used for combustion. The gases are separated and redirected into the intake via the EGR (exhaust gas recirculation valve).
The process of containing the crankcase gases in the engine is a messy process. It’s not a perfect system because of the inability to get 100% of the gases recirculated. The bus drivers have to do their part when they see the DPF (diesel particulate filter) dash light come on.
When the light stays on steady they can either try to do a parked regen using the dash regen switch that comes from the factory or drive the bus hard for 20 minutes to get the engine heated up to it’s maximum temperature which might aid in cleaning out the DPF to the point where the warning light goes out.
If the light continues to stay on a parked regen is mandatory. The vehicle can still be driven until the warning light starts to flash then the bus will go into a slight derate condition. When the light flashes along with a malfunction indicator lamp the engine will derate even more to give the operator a hint that it’s is definitely time to pull over and do the parked regen.
Then finally the red stop engine light will come on and the engine will de-rate down to a crawl and that’s it…you’re stuck until you either take the vehicle to a shop using a tow truck or if you’re desperate you could open the exhaust system before the DPF and limp your rig home.
This can be avoided very easily by running the engine hot enough to keep the exhaust system clean, doing a parked regen on a regular maintenance schedule or stopping immediately after you see the DPF regen warning light come on and push the regen dash switch.
The regeneration process for emission controlled diesel engines is here to stay so we have to live with the inconveniences that come with this technology. The main idea of course is to keep our air clean and free of cancer causing carcinogens that cause ill health to the population especially children and the elderly. Thanks for reading this article and please post a comment below.