Early Spring Greetings from the Nappanee….
Not so long ago, "idle time" in the RV realm meant quiet, relaxing moments spent watching sunsets or depleting your favorite fishing spot of inventory. When someone talks to you about "idle time" now around the campfire, they might just be talking about something else….
With the introduction of the new "ultra low sulfur diesel fuels" and lower emissions "After treatment" systems on diesel powered products, conversations about "idle time" now may swirl around how long to allow units to idle… or not idle!
Starting with the 2008 model year, some diesel chassis units use a special system specifically designed to lower emissions. Part of this system is a "DPF", or "Diesel Particulate Filter" built into the exhaust stream, which catches diesel soot. Over time this material builds up, and the filter must be cleaned. This is accomplished automatically by a system called "Regeneration", which essentially is a process of heating the filter until these materials are turned into carbon dioxide. In normal use (when traveling, for example) the exhaust will build sufficient heat to allow this process to occur as needed.
Extensive idling, however, can cause considerable build up of materials on the DPF, and can cause potential running problems with the unit. Units equipped with this system will have a "DPF" light on their dash warning cluster that will illuminate when the DPF needs regeneration. The cure is simple; take the unit out and drive it. Usually 20 - 30 minutes of highway driving will take care of the regeneration need.
There can be a little confusion, though. On some early production 2008 units, the light was programmed to come on any time the system went into the regeneration mode. Nothing was wrong with the unit, the system was just doing its job automatically, and the light was triggered to let you know it was doing just that. However, since a dash light coming on usually meant something was wrong, many confused this with a problem with the system, so later model units were programmed so they do not turn the light on when regeneration is underway.
So what does all this mean? Basically, the chassis and engine manufacturers recommend limiting idle time. Most units will be able to idle between 4-6 hours before regeneration is required, but as previously stated, if the "DPF" light comes on, it's time to take the unit for a ride to regenerate the system. The estimated time between regeneration cycles is usually over 100 hours in normal use, but keep in mind this is NOT idling time, and it will all certainly be dictated by how the unit is driven and used. Regeneration will not occur while idling, or often will not occur at speeds below 25 mph.
One other condition to be aware of is if the "High Exhaust Temperature" light comes on, it is indicating that the system has regenerated, and the exhaust components and gases are extremely hot. Use caution not to park the unit where the exhaust system can come in contact with flammable materials, or where the exhaust gases may melt or ignite anything.
The best source for information on your particular unit is the Chassis Manual that was supplied with your unit by the chassis manufacturer. The information applicable to your chassis and powertrain will be found there.