EPA07 Aftertreatment System (ATS) Guideline

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All on-road diesel engines built after December 31, 2006, (EPA07 engines) must meet strict new guidelines for reduced exhaust emissions of particulate matter and nitrogen oxides (NOx). NOx is limited to just over 1 gram per brake horsepower hour (g/bhp-hr) and particulate matter cannot exceed 0.01 g/bhp-hr.

EPA07-compliant engines require ultralow-sulfur diesel (ULSD) fuel, and they should never be run on fuel with sulfur content higher than 15 ppm. In addition, they require low-ash engine oil. The following guidelines must be followed or the warranty may be compromised.

  • Use ultralow-sulfur diesel (ULSD) fuel with 15 ppm sulfur content or less, based on ASTM D2622 test procedure.

  • Do not use fuel blended with used engine lube oil or kerosene.

  • Engine lube oil must have a sulfated ash level less than 1.0 wt %; meeting the API CJ-4 index specifications.

Important: Using non-specification fuels or oils can lead to shortened Diesel Particulate Filter (DPF) cleaning or exchange intervals. For example, using CI-4+ oil with 1.3% sulfated ash (30% more ash content) may result in the need for DPF cleaning or exchange 20 to 30% sooner than would normally be required.

The 'exhaust system' in EPA07-compliant vehicles is called the aftertreatment system (ATS). The ATS varies according to engine manufacturer and vehicle configuration, but instead of a muffler, an aftertreatment system has a device that outwardly resembles a muffler, called the aftertreatment device (ATD).

Important: See your engine operation manual for complete details and operation of the aftertreatment system.

Inside the ATD, the exhaust first passes over the diesel oxidation catalyst (DOC), then it passes through the DPF, which traps soot particles. If exhaust temperature is high enough, the trapped soot is reduced to ash in a process called passive regeneration (regen). Passive regeneration occurs as the vehicle is driven normally under load; the driver is not even aware that it is happening. The harder an EPA07 engine works, the better it disposes of soot, as the exhaust heat alone is enough to burn the soot to ash. Over the course of a workday, however, passive regeneration cannot always keep the ATD filter clean, so the filter must undergo active regeneration. In active regeneration, extra fuel is injected into the exhaust stream to superheat the soot trapped in the DPF and turn it to ash. Active regeneration happens only when the vehicle is moving above a certain speed, determined by the engine manufacturer. Consult manufacturers' documentation for details.

Both active and passive regeneration happen automatically, without driver input.

Only when operating conditions do not allow for ATD filter cleaning by at-speed active or passive regeneration, the vehicle may require a driver-activated parked regeneration. The vehicle must be standing still, and the driver must initiate parked regen. Completing a parked regen takes 20 minutes to an hour, depending on ambient conditions.

Fig. 1, Diesel Particulate Filter (DPF) Status Lamp

Fig. 2, High Exhaust System Temperature (HEST) Lamp

Danger: During parked regeneration, 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 regeneration, 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.

The warning lamps in the driver message center alert the driver of a regen in progress, of high exhaust temperatures, of the need to perform a parked regen either soon or immediately, and of an engine fault that affects the emissions.

A slow (10-second) flashing of the high exhaust system temperature (HEST) lamp indicates that a parked regen is in progress, and the engine's high idle speed is being controlled by the engine software, not the driver.

A steadily illuminated HEST lamp alerts the operator of high exhaust temperature during the regeneration process, if vehicle speed is below 5 mph (8 km/h). See Fig.. The HEST lamp does not indicate the need for any kind of vehicle or engine service; it only alerts the vehicle operator of high exhaust temperatures. Make sure the engine exhaust pipe outlet is not directed at any person, or at any surface or material that will melt, burn, or combust.

Warning: When the HEST lamp is on, be certain that the exhaust pipe outlet is not directed at combustible material or toward anyone. To do so could cause damage to the vehicle and serious personal injury to others.

Warning: Active regeneration can occur automatically anytime the vehicle is moving. The exhaust gas temperature could reach 1500°F (816°C), which is hot enough to cause a fire, heat damage to objects or materials, or personal injury to persons near the exhaust outlet. See Regen-Inhibit Switch later in this chapter for instructions on preventing automatic regen if necessary.

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.

Important: Due to the high exhaust temperature during the regen process, a diffuser is used to reduce the temperature at the exhaust pipe outlet. See Fig.. If the diffuser is damaged, it must be replaced to ensure proper operation of the vehicle and to reduce the possibility of damage or injury.

Fig. 3, Exhaust Diffuser

A steadily illuminated yellow DPF lamp indicates a regen is required soon. Bring the vehicle to highway speeds to allow for an active regen, or a parked regen should be scheduled for the earliest convenient time. See Fig..

Important: Failure to regen could cause engine problems, including derate or loss of power. As soon as allowed after the DPF lamp illuminates, maintain highway speeds to allow automatic regeneration, or park the vehicle in a safe location and perform a parked regen.

A DPF lamp blinking at the same time as a steadily illuminated yellow Check Engine lamp indicates that a parked regen must be performed immediately, or an engine derate will occur. If the red Stop Engine lamp illuminates with the blinking DPF lamp and the yellow Check Engine lamp, a parked regen must occur or an engine shutdown will occur. Park the vehicle and perform a parked regen. See Fig. and Fig..

  1. Malfunction Indicator Lamp (MIL)

  2. Check-Engine Lamp

  3. Stop-Engine Lamp

Fig. 4, Engine Protection Lamps

Fig. 5, Regen Switch

The DPF regen switch, located on the dash, may have three selectable positions:

  • Request Regeneration

  • Default (can include appropriate normal state conditioneither in an automatic regeneration or inhibit state)

  • Inhibit regeneration (optional when available)

Note: The regen switch can start a regen only when at least one of two conditions exists: either the DPF lamp is lit, or the engine software calls for it. If neither of those conditions exist, the regen switch cannot cause a regen to happen.

The function of the switch will vary by the engine make and model in the vehicle. See the engine operation manual for switch operation details.

When diesel particulate filter servicing is needed, it must be performed by an authorized technician, and a record must be maintained for warranty purposes. The record must include:

  • date of cleaning or replacement

  • vehicle mileage

  • particulate filter part number and serial number

A steadily illuminated Malfunction Indicator Lamp (MIL) indicates an engine fault that affects the emissions. See Fig. .

Note:
Parent topic: EPA07 Aftertreatment System (ATS)
Document Number: 0000119392
Manual Publication Date: 2024-05-17
Topic Publication Date: 2024-05-13