For owners of diesel trucks, especially those with the robust 6.7 Cummins engine, staying informed about emission regulations is crucial. New Smog Check requirements are on the horizon, and understanding how your OBD2 monitor system is affected is key to compliance. Starting July 2023, California’s Bureau of Automotive Repair (BAR) is updating the Smog Check program for 2007 and newer light-duty diesel vehicles, impacting how On-Board Diagnostic (OBD) readiness monitors are assessed. These changes are designed to further reduce diesel emissions and align with clean air objectives.
What are OBD2 Readiness Monitors and Why Do They Matter?
Since 2010, diesel vehicles from model year 1998 onwards (with a gross vehicle weight rating under 14,001 pounds) have been part of the Smog Check Program. A core component of this inspection is evaluating the OBD II system. This system uses “readiness monitors,” which are essentially self-tests run by your vehicle to ensure its emission control systems are functioning correctly. Think of them as internal health checks for your truck’s pollution controls. To pass a smog check, these monitors need to be in a “ready” state, indicating successful completion of their tests.
For older vehicles (1998-2006), all readiness monitors had to be set. However, recognizing the increased complexity of exhaust systems in newer diesels, vehicles from 2007 onwards were allowed to have up to two monitors unset and still pass. This leniency is now changing.
Stricter Readiness Standards for 2007+ Diesel Vehicles: Focus on DPF and NMHC Monitors
The significant update for July 2023 is that the allowed number of unset readiness monitors for 2007 and newer light-duty diesel vehicles is being tightened. Now, only the Diesel Particulate Filter (DPF) monitor and the Non-Methane Hydrocarbon Catalyst (NMHC) monitor are permitted to be unset. This means that all other emission-related monitors must be in a “ready” state for your 6.7 Cummins or other compliant diesel truck to pass the Smog Check.
Alt text: A handheld OBD2 monitor tool displaying diagnostic information from a vehicle’s computer system, highlighting the complexity of modern vehicle emissions monitoring.
This shift emphasizes the critical role of components like the DPF and NMHC catalyst in reducing harmful emissions from diesel engines. For 6.7 Cummins owners, ensuring these systems, and their associated monitors, are functioning correctly will be paramount for passing future smog checks. A fault in other systems that previously might have been overlooked could now cause a failure if the corresponding OBD2 monitor is not ready.
Exemptions for Certain Vehicles
It’s worth noting that some vehicles may have design limitations preventing them from meeting these stricter monitor readiness standards. The BAR acknowledges this and will automatically exempt these vehicles during the Smog Check inspection using their On-Board Diagnostic Inspection System. This exemption process will be transparent to the vehicle owner and the Smog Check inspector, requiring no manual input.
What This Means for Your 6.7 Cummins and Diesel Smog Checks
For owners of 6.7 Cummins powered trucks and other modern light-duty diesel vehicles, these new regulations mean increased scrutiny on your vehicle’s emission control systems. While the focus remains on OBD2 monitors, the tightening of standards underscores the importance of maintaining all emission-related components in good working order. Pay particular attention to systems beyond just the DPF and NMHC catalyst, as issues with other emission controls can now directly impact your ability to pass a smog check due to readiness monitor requirements.
Staying Informed
For a comprehensive overview of readiness standards and a list of potentially exempted vehicles, the Bureau of Automotive Repair provides resources online. Refer to the On-Board Diagnostic Test Reference webpage at www.bar.ca.gov for detailed information.
Conclusion
The upcoming changes to diesel Smog Check requirements, particularly concerning OBD2 readiness monitors, are significant for diesel vehicle owners. Understanding these new standards, especially the focus on DPF and NMHC monitors while minimizing allowable unset monitors, is vital for ensuring your 6.7 Cummins or other diesel truck remains compliant and on the road. Regular maintenance and prompt attention to any warning lights related to your emission system will be more important than ever as these new rules take effect.
