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California Air Resources Board Announces New Clean Truck Check OBD Requirements

The California Air Resources Board (CARB) has announced that new Clean Truck Check OBD requirements will be instituted sometime in early 2024.

When it was launched in 2023, the Clean Truck Check OBD requirement - which applies to diesel and diesel hybrid heavy-duty vehicles model 2013 and newer as well as other alternatively fueled (such as natural gas) heavy duty vehicles model 2018 and newer - tested only diagnostic trouble codes (DTC). The new rule will require testing Permanent Diagnostic Trouble Codes (PDTC) as well.

CARB states that DTCs weren't sufficient for monitoring the effectiveness of the Emissions Control Systems (ECS) and identifying ECS in need of repair. DTCs can be reset by, "disconnecting the vehicle's battery or cleared using an OBD scan device. The only way to clear a PDTC is to fix the underlying problem with the vehicle that originally caused the PDTC to set, and then allow the vehicle sufficient drive time to re-run the Monitor that identified the problem in the first place...Unplugging the vehicle’s battery or using a scan device to 'clear codes' are techniques sometimes used to clear OBD information from a vehicle that has an illuminated [Malfunction Indicator Light] in an attempt to hide the fact that the vehicle is malfunctioning."

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