Big Changes

If you are a regular reader of Fleet Maintenance magazine, you've seen countless articles on the technologies related to the 2007 diesel emissions standards mandated by the Environmental Protection Agency (EPA). Anna Wells also made reference to the training impact in her April, 2006 Medium-Duty article: "Keeping up with the Times." But what, specifically, are some issues related to these engines that may require training? If your fleet is planning to add new vehicles in 2007, you need to know what you'll be seeing in your shop.


The EPA has mandated the conversion to Ultra Low Sulfur Diesel (ULSD) fuel. Technicians need to be aware of the impact that using the wrong fuels may have on a 2007 diesel engine—not only the engine performance impact but the potential of incorrect fuels to foul and damage certain components.


Most 2007 diesel engines will require the use of Low Ash CJ-4 engine oils to complement the new aftertreatment systems. Again, technicians will need to know the impact of using incorrect engine oils.


Even if your fleet runs fairly recent diesel engine vehicles with EGR systems, the systems on 2007 diesels will likely be even more complex. Particularly, the cooling of recirculated exhaust gases has become even more important for meeting 2007 oxides of nitrogen (NOx) standards. Enhanced EGR cooling systems, larger coolers or even dual coolers may be used on the newest engines. EGR catalysts may also be incorporated in the EGR down-pipe to reduce NOx before the exhaust gases reach the engine to be re-burned.


Unless your diesel engine technician has been through a recent gasoline engine performance course or comes from that background, the use of oxidation catalysts (catalytic converters) and ECM monitoring strategies for emissions components will be all new. 2007 diesel engines must meet On-Board Diagnostics II (OBD II) regulations similar to those that have been placed on gasoline engines for over ten years. Along with a solid knowledge of OBD II, technicians will need to learn about specific OBD II monitors for diesels and how to diagnose trouble codes related to a monitor.

An additional part of the exhaust aftertreatment system is the Diesel Particulate Filter (DPF). The DPF has the specific function of trapping and periodically burning off diesel particulate matter, or "soot." The process of burning off trapped soot is called "regeneration," and is controlled by the ECM as it monitors inlet and outlet pressures for the DPF. Regeneration occurs normally when the vehicle is driven at higher speeds for a certain period of time (usually highway driving is required). If your fleet has vehicles that are rarely driven at highway speeds, your operators might see a confusing instrument cluster lamp or message indicating that a regeneration event was unable to be performed. Your technicians will need to know how to interpret these messages and perform a manual regeneration.

Furthermore, not all of the soot in the DPF can be burned off. Some remains stored in the filter as non-burnable ash. Therefore, the DPF itself has a maintenance interval of which the technician must be aware.


There are a number of safety issues—from high pressure fuel system warnings to handling of high heat components—that are required for a technician to work on 2007 diesel engines. In addition, technicians must be aware of Federal regulations regarding emissions component tampering, plus proper tagging, documentation and disposal of catalytic converters and particulate filters.


The EPA regulations for diesel engines vary based on vehicle weight class. Therefore, some engines on light-duty vehicles may have additional components (such as oxygen sensors) that are not found on medium-duty or even heavier light-duty vehicles. A thorough knowledge of the engine control systems for each type of new vehicle in your fleet will be essential to proper diagnosis.

Stephen Howe is employed by Tweddle Litho Company, a global provider of information development, management and delivery that has served the automotive and heavy vehicle industries for over 50 years.

Stephen is also a past president of the Automotive Training Managers Council (ATMC), a global, non-profit organization of over 60 member companies dedicated to recognizing training excellence and raising training standards in the automotive, heavy vehicle and related industries.