BAR's 2026 OBD readiness monitor regulations explained

To strengthen the effectiveness of the California Smog Check Program, the Bureau of Automotive Repair (BAR) has officially adopted new regulations regarding On-Board Diagnostic II (OBD II) readiness monitors. Effective October 1, 2025, these rules require that all readiness monitors must be set for a vehicle to pass its Smog Check inspection.

This change marks a shift from the previous "allowance" system to a more data-driven, phased implementation designed to ensure vehicles are truly meeting clean air standards before they are certified.

Why the Change? The Role of Readiness Monitors

Readiness monitors are essentially "self-tests" your car’s computer runs to verify its emissions controls are working. When you clear a diagnostic code or disconnect your battery, these monitors reset to "Not Ready." Historically, BAR allowed certain monitors to remain unset because some were notoriously "hard to set" during a normal drive.

However, these broad exemptions inadvertently allowed some vehicles to pass even with malfunctioning emissions systems. The new 2026 standards aim to close these loopholes, preventing costly, unexpected repairs for future owners and ensuring California’s air stays clean.

The Phased Implementation Strategy

While the regulation technically requires all monitors to be set, BAR is using a practical, phased approach to ensure neither drivers nor the industry are overwhelmed.

Data-Driven Updates: For now, the previous pass/fail criteria (see chart below) remain the baseline while BAR collects real-world data.

Gradual Tightening: Standards will only be tightened for specific vehicle makes and models once data confirms that their monitors can reasonably be expected to set through normal driving.

Permanent Exceptions: For vehicles with unique design issues that make setting certain monitors nearly impossible, BAR—in consultation with CARB—will grant permanent exceptions.

Current Readiness Monitor Standards (Late 2025–2026)

Until further notice, the following standards serve as the active criteria during the phased rollout:

Vehicle Fuel Type

Model Years

Readiness Monitor Exception Allowed

Gasoline

1996–1999

Any one unset monitor allowed.

Gasoline

2000 and newer

Only the Evaporative (EVAP) monitor may be unset.

Diesel

1998–2006

No unset monitors allowed.

Diesel

2007 and newer

Only the DPF and NMHC Catalyst may be unset.

Challenges and Solutions for Drivers

The biggest hurdle for drivers in 2026 is the "Not Ready" failure after a simple battery change or repair. To avoid a "No Pass" result, keep these tips in mind:

The 2-Week Rule: Most properly functioning vehicles can set all required monitors within two weeks of normal driving.

The Drive Cycle: If a monitor won't set, consult your owner’s manual for a specific "Drive Cycle"—a series of speeds and conditions required to trigger the computer's self-test.

Consult the Referee: If you have followed a drive cycle and your monitors still won't set, the Smog Check Referee is available to assist. They can provide third-party evaluations and determine if your vehicle qualifies for a design-related exception.

Final Thoughts for Shop Owners and Technicians

Stay informed through BAR’s ET Blasts and the Smog Check Reference Guide. As BAR analyzes 2026 data, changes to the "unset" criteria will be announced well in advance. Ensuring your customers understand the importance of a proper drive cycle before their appointment will reduce frustration and improve your shop’s efficiency.

Pro-Tip for 2026 Compliance

If your vehicle has persistent "Not Ready" monitors after a week of driving, do not keep clearing the codes. Every time you clear a code or disconnect the battery, the process starts over from zero. Instead, follow the manufacturer’s specific Drive Cycle, which usually involves:

Starting the engine cold and idling for 2–3 minutes.

Driving at a steady 55 mph for 10 minutes without using cruise control.

Allowing the vehicle to coast down to 20 mph without touching the brakes.