Beginning next year, motorcoach technicians will have to deal with a significant increase in possible engine fault codes because of the onboard diagnostics systems that will come with 2010 and later model engines.

In the past, mechanics essentially had two fault codes they could work with on a sensor. Now, with onboard diagnostics, that same sensor has five codes.

U.S. Environmental Protection Agency regulations require 2010 and later model-year engines to be bundled with diagnostics that use an array of sensors to monitor the new emissions-control systems (see April 1 Bus & Motorcoach News).

If a coachs emissions of nitrogen oxides or particulate matter exceed certain thresholds, the onboard diagnostics system must alert the driver via a dashboard signal.

The additional fault codes appear because the onboard diagnostics systems monitor emissions performance, a measurement that was not required before the EPAs 2010 mandate.

The upside for technicians is that no new equipment is required to read and interpret the new fault codes when an emissions level gets out of whack.

In other words, the technicians job hasnt changed pre-onboard diagnostics and post- onboard diagnostics. He or she uses the same voltmeter, the same troubleshooting guide and the same laptop computer to process fault codes.

Technicians working at engine manufacturer distributors and dealerships, however, will need more training to deal with the additional complexities of the onboard diagnostics systems.

For example, Detroit Diesel, which has about 22,000 technicians at its outlets, has set up a web-based training module that it will require all of its technicians to complete.

Besides the web module, one technician from each Detroit Diesel service facility will be required to attend a second level of training.

Starting in 2010, Detroit Diesel engines will only be available in Setra motorcoaches.

Navistar Inc., maker of IC buses and coaches, also is leaning on software to help train field technicians. For 2010, it will have two web-based training programs. One will cover the changes in the 2010 engine, versus the current models, and the second will cover the changes in the diagnostics.

While technicians will receive additional training to familiarize them with onboard diagnostics, they will still use the same hardware and software the company already uses to process fault codes. Navistar has about 7,000 field technicians in its network.

Navistar is the only engine maker in the North American market that is not using selective catalytic reduction to meet EPAs 2010 emission cuts. However, the company still must comply with the onboard diagnostics mandate.

The coach industrys other two 2010 engine suppliers, Cummins and Volvo, will be using selective catalytic reduction for their power plants and, of course, must have the onboard diagnostics.

Automobiles have used onboard diagnostic systems since the mid-1990s. Heavy-duty diesel engines will use these systems for the first time in 2010.

As a result, EPA has decided on a gradual phase-in of the diagnostics mandate. For example, only one engine family per manufacturer will have to use onboard diagnostics in 2010.

Moreover, onboard diagnostics systems in 2010 will not be required to trigger a warning light until regulated emissions rise to more than double EPA 2010 levels.

By 2019, all engine families from all manufacturers will have to use onboard diagnostics systems, and detection thresholds will tighten so that any breach of the 2010 emissions standard will trigger a warning light, EPA said.