This comprehensive guide outlines the pass/fail criteria for Eco Obd2 Diesel Tests during Smog Check inspections. It also provides detailed instructions for inspecting vehicles known to have OBD test difficulties, focusing on diesel models.
Understanding Eco OBD2 Diesel Testing
Eco OBD2 testing for diesel vehicles plays a crucial role in Smog Check inspections, ensuring compliance with emission standards. This system monitors various emission control components and reports their functionality through readiness monitors. While most vehicles complete these monitors during regular driving, some diesel models experience difficulties due to specific operating conditions or infrequent use in required driving modes. This document addresses common issues and provides guidance for inspectors.
Pass/Fail Standards for Eco OBD2 Diesel Tests
Readiness Monitor Standards for Diesel Vehicles
Readiness monitors are self-diagnostic tests performed by the vehicle’s OBD system. The number of incomplete monitors permissible for passing the OBD test varies by model year and fuel type. For diesel vehicles:
- 1998-2006: Zero incomplete monitors allowed.
- 2007 and newer: Only the Particulate Filter and Non-Methane HydroCarbon (NMHC) monitors are allowed to be incomplete. This standard was implemented on July 5, 2023, reflecting updates in diesel emission technology.
Malfunction Indicator Lamp (MIL) Standards
The MIL, often referred to as the “Check Engine” light, provides crucial diagnostic information:
- Pass: MIL illuminates during Key On Engine Off (KOEO) and turns off during Key On Engine Running (KOER).
- Fail: MIL doesn’t illuminate during KOEO or remains illuminated during KOER.
Communication Standards
Communication failures can occur due to various reasons, including a damaged OBD connector, aftermarket modifications, or invalid data transmission:
- BAR-97: Vehicle must communicate with the BAR-97 system.
- OIS: Vehicle must communicate with the OIS and transmit necessary data, typically from specific OBD addresses (Mode $01 PID $00 and Mode $01 PID $01).
Permanent Diagnostic Trouble Code (PDTC) Standards
Implemented on July 1, 2019, the PDTC check adds another layer to the inspection process:
- 2010 and newer diesel vehicles: A stored PDTC results in an automatic failure, regardless of MIL status. However, specific exceptions exist for certain vehicles known to have PDTC clearing issues. Consult Section E: Permanent Diagnostic Trouble Code Vehicles of Interest for details.
Diesel Vehicles of Interest in OIS Inspections
This section lists specific diesel models with known OBD test issues.
| Make | Year | Model Engine | Issue | Cause and Possible Remedy | Instruction to Inspector |
|---|---|---|---|---|---|
| Chevrolet | 1998-2005 | C/K2500 & C/K3500 (diesel) | Federal diesel vehicles over 8,500 GVWR are not OBD-II certified. | These vehicles were not manufactured to comply with OBD-II standards. | Test normally. BAR-OIS will ignore incomplete continuous monitors. If communication failure occurs, use the bulb check result for the overall OBD test result if available on the analyzer. |
| Chevrolet | 1999-2005 | 3500 W35042 (diesel) | Vehicle lacks OBD II. | OBD systems were not installed in federal vehicles during these years. | OIS is programmed to bypass the OBD functional test. |
| Dodge/Ram | 2010-2015 | 2500 & 3500 6.7L (diesel) | NOx after-treatment monitor incompletion. | Vehicle design anomaly. | Test normally. BAR-OIS temporarily allows an incomplete NOx after-treatment monitor until a manufacturer remedy is available. |
Conclusion
Eco OBD2 diesel testing is critical for maintaining air quality standards. This guide provides essential information for conducting accurate inspections and addressing common issues encountered with diesel vehicles. Refer to the detailed tables for specific vehicle information and troubleshooting guidance. Staying informed about updates to regulations and vehicle-specific issues ensures efficient and effective Smog Check inspections.
