Readiness monitors and trouble codes answer different questions
What a readiness report can tell you
California BAR describes readiness monitors as OBD self-tests for emissions-control functionality. Completion can depend on operating conditions and functioning components. A monitor that has not completed is not, by itself, a name for a failed replacement part.
Source: California BAR: On-Board Diagnostic Test Reference — current inspection guidance
Why a universal mileage promise is misleading
BAR notes that required operating conditions can include speed, temperature, pressure and engine load. Some procedures are in an owner’s manual, while others require service information. Its guidance also explains that readiness tests may need to run again after work such as battery disconnection. A single promised mileage or an invented drive cycle cannot cover all these conditions.
Source: California BAR: On-Board Diagnostic Test Reference — current inspection guidance
Separate the readings in your notes
Our suggested inspection-preparation record has separate spaces for the scanner’s readiness labels, stored code labels and warning-light behavior. Copy the terminology exactly, including whether a monitor is unsupported rather than incomplete. Add the vehicle’s year, fuel type and market. Record any battery work or code clearing with its date if known. Leave unknown information blank instead of inferring it from the code prefix.
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Check the rule that actually applies
The BAR reference is for California Smog Check. It distinguishes readiness, malfunction-lamp, communication, permanent-code and software standards, and includes vehicle-specific exceptions. Consult the live reference and the inspection authority for your location; an example from another jurisdiction is not your pass/fail rule.
Source: California BAR: On-Board Diagnostic Test Reference — current inspection guidance
Use a repeatable comparison
When a workshop or inspection station requests another scan, preserve the earlier report and compare like-for-like fields. Record what changed and what remains incomplete without replacing the original observations. Ask whether the next step is a vehicle-specific operating procedure, diagnosis of an enabling condition or review of an inspection exception. Our worksheet supports that conversation; it does not calculate an inspection pass or certify emissions compliance.
Sources and scope
Sources checked on 7 September 2026. This AI-assisted reference explains source material and offers record-keeping suggestions. It has not been presented as a mechanic’s inspection of your vehicle. Consult the original source for its current requirements.
How we handle sources and corrections