Regeneration
The harder an engine works, the better it disposes of soot. If the exhaust temperature is high enough, a process called passive regeneration (regen) occurs as the vehicle is driven normally. However, if the engine isn't running hot enough, the electronic controls may initiate an active regen , whereby extra fuel is injected into the exhaust stream to superheat and reduce the soot trapped in the DPF to ash. Active regen happens only when the vehicle is moving above a certain speed, determined by the engine manufacturer. See your engine operation manual for complete details. Both active and passive regen happen automatically, without driver input.
Warning: Active regeneration can occur automatically anytime the vehicle is moving. The exhaust gas temperature could reach 1500°F (800°C), which is hot enough to cause a fire, heat damage to objects or materials, or personal injury to persons near the exhaust outlet. The exhaust temperature can remain high even after the vehicle has stopped. When stopping the vehicle shortly after an automatic regen, ensure the exhaust outlets are directed away from structures, vegetation, flammable materials, and anything else that may be harmed by exposure to high heat.
See Regen Switches , below, for instructions on preventing automatic regen if necessary.
When operating conditions do not allow for ATD filter cleaning by active or passive regen, the vehicle may require a driver-activated parked regen . When this occurs, the DPF lamp illuminates, indicating that a regen is required. The driver must either bring the vehicle up to highway speed to increase the load (thus starting an active regen), or park the vehicle and initiate a parked regen. See Regen Switches , below, for instructions on initiating a parked regen.
Regen Switches
The regen request switch, located on the dash, is used to initiate a parked regen. See Fig., item 1. The function of the switch varies by the engine make and model in the vehicle. See the engine operation manual for switch operation details.
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Regen Request Switch
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Regen Request/Inhibit Switch
Fig. 1, Aftertreatment System Regen Switches
Some vehicles may be equipped with a regen request/inhibit switch. See Fig., item 2. To stop a regen in progress or prevent the start of a regen, press the lower half of the switch. Regen is then delayed until the switch is no longer active.
Note: The regen switch can initiate a parked regen only when the DPF lamp is illuminated.
Warning: During parked regen, exhaust temperatures are very high and could cause a fire, heat damage to objects or materials, or personal injury to persons near the exhaust outlet.
Before initiating a parked regen, make certain the exhaust outlets are directed away from structures, vegetation, flammable materials, and anything else that may be harmed by prolonged exposure to high heat.