OBD TESTING — CALIFORNIA HEAVY-DUTY VEHICLES
OBD Testing for Heavy-Duty Vehicles — California
On-board diagnostics (OBD) testing is a key component of California's Clean Truck Check program, which requires qualifying heavy-duty commercial vehicles to undergo regular emissions-related inspections. OBD testing reads diagnostic trouble codes and emissions system data directly from a vehicle's onboard computer, helping verify that a truck's emissions controls are functioning as required. Air Compliance Testing (ACT) performs applicable OBD diagnostic testing as part of its mobile Clean Truck Check service — coming directly to your fleet yard, business location, or qualifying on-site address throughout California.
How OBD Testing Works for Heavy-Duty Vehicles
Understanding on-board diagnostics testing in the context of California's Clean Truck Check compliance program.
What Is OBD?
On-board diagnostics (OBD) is a standardized system built into modern commercial vehicles that continuously monitors engine performance, emissions controls, and related systems.
Reading Diagnostic Data
During an OBD test, a certified technician connects diagnostic equipment to the vehicle's OBD port to read stored fault codes, emissions readiness monitors, and system status data.
Emissions Readiness Monitors
The test checks whether the vehicle's onboard emissions monitors — such as catalyst, oxygen sensor, and EGR system monitors — have run and report a passing or ready status.
Heavy-Duty Application
California's Clean Truck Check program uses OBD testing as one method to verify emissions compliance for qualifying heavy-duty diesel and alternative-fuel commercial vehicles.
On-Site Capability
ACT's mobile technicians carry calibrated OBD diagnostic tools, enabling applicable OBD testing to be performed at your location without requiring vehicles to travel to a fixed inspection station.
Compliance Documentation
Testing results support the vehicle owner's ability to demonstrate compliance with CARB Clean Truck Check requirements and maintain accurate fleet compliance records.
Which Vehicles and Operators May Require OBD Testing?
California's Clean Truck Check program establishes which vehicle types and model years are subject to testing requirements. OBD testing may apply to heavy-duty diesel and alternative-fuel commercial vehicles of specified model years operating in California. The following categories of owners and operators should verify whether their vehicles fall within Clean Truck Check testing requirements.
Owner-Operators
Trucking Companies
Delivery Fleets
Construction Fleets
Logistics Companies
Transportation Companies
Fleet Managers
Businesses Operating Heavy-Duty Vehicles
Vehicle eligibility is determined by model year, GVWR, and fuel type as specified in CARB's Clean Truck Check regulations. ACT recommends contacting us to confirm whether your specific vehicle(s) fall within current testing requirements.
Mobile OBD Testing — We Come to You
Air Compliance Testing (ACT) performs applicable OBD diagnostic testing as part of its mobile Clean Truck Check service. A credentialed ACT technician travels to your fleet yard, business location, or qualifying on-site address — equipped with the diagnostic tools required to perform applicable OBD testing on heavy-duty commercial vehicles.
No need to transport vehicles to a fixed testing station
Technicians carry calibrated OBD diagnostic equipment
Applicable to individual trucks and commercial fleets
On-site testing at qualifying California locations
Mobile service across ACT's California service territory
Scheduling coordinated directly with ACT
ACT serves commercial truck owners and fleets throughout California. Contact ACT to confirm vehicle eligibility and schedule mobile OBD testing at your location.
OBD Testing — Frequently Asked Questions
Answers to common questions about on-board diagnostics testing for heavy-duty commercial vehicles in California.
What is OBD testing?
OBD testing, or on-board diagnostics testing, is a process in which a technician connects diagnostic equipment to a vehicle's OBD port to read emissions-related data, fault codes, and system readiness monitor status from the vehicle's onboard computer. In the context of California's Clean Truck Check program, OBD testing is used to verify that qualifying heavy-duty commercial vehicles' emissions control systems are operating as required.Does ACT perform OBD testing?
Yes. Air Compliance Testing (ACT) performs applicable OBD diagnostic testing as part of its mobile Clean Truck Check service. ACT technicians are credentialed and equipped with the tools required to perform applicable OBD testing on heavy-duty commercial vehicles at your location throughout California.What vehicles require OBD testing in California?
California's Clean Truck Check program specifies which vehicle types — by model year, gross vehicle weight rating (GVWR), and fuel type — are subject to testing requirements, which may include OBD testing. Generally, qualifying heavy-duty diesel and certain alternative-fuel commercial vehicles operating in California may be subject to Clean Truck Check testing. ACT recommends contacting us to confirm whether your specific vehicle(s) fall within current testing requirements.How is OBD testing performed on-site?
An ACT credentialed technician travels to your agreed location — fleet yard, business address, or qualifying on-site location — carrying calibrated OBD diagnostic equipment. The technician connects the diagnostic tool to the vehicle's OBD port, retrieves stored data and readiness monitor status, and documents the results as part of the Clean Truck Check testing process. The on-site process is designed to minimize vehicle downtime and avoid the need to transport trucks to a fixed testing station.
Ready to Schedule Mobile OBD Testing?
Air Compliance Testing (ACT) provides mobile Clean Truck Check testing — including applicable OBD diagnostic testing — for California commercial truck owners and fleets. Request a quote or schedule testing today.