Best practices for improving STAR scores
The STAR program, created pursuant to Assembly Bill 2289 (Eng, Chapter 258, Statutes of 2010), aims to improve the overall quality of Smog Check inspections and help California meet its emissions reduction goals. This voluntary certification program is available to Smog Check test-and-repair and test-only stations that meet high inspection standards.
STAR report card
The STAR Report Card provides performance scores for stations and inspectors. It includes two key metrics:
- Short-term measures
- Follow-up pass rate (FPR)
To provide a fair and unbiased assessment, these performance measures compare vehicles inspected by each station and inspector to similar vehicles inspected by stations and inspectors throughout the state.
Short-term measures
Short-term measures identify testing patterns that deviate from expected results by comparing them to millions of inspections performed statewide. These measures can help stations identify areas to improve their overall performance. For example, if a station fails to perform fuel evaporative or timing functional tests on vehicles that require them, the short-term measures will note the deviation and flag the vehicle for future reference. Short term measures do not identify incomplete visual or timing inspections nor do they identify fraud, such as clean piping, clean plugging, or clean tanking. Fraudulent or incomplete inspections, however, are detected in the FPR.
Follow-up pass rate
The FPR measures the rate at which vehicles certified by each licensed Smog Check station and inspector passes or fails a follow-up inspection in their next cycle. It is a more robust and long-term measure of station and inspector performance and actions or inspection omissions not identified by the short-term measures. FPR scores range from zero (lowest) to 1 (highest). Scores above .50 indicate that vehicles are passing inspections in the next cycle at a higher-than-expected rate. Inversely, an FPR score below .50 indicates that vehicles are failing at a higher-than-expected rate. STAR stations should strive to maintain a score above .50. Stations and inspectors with insufficient inspection history to calculate an FPR score receive a "No Score."
FPR factors
FPR scores take vehicle characteristics such as make, model, age, or mileage, into account. Inspecting older, higher mileage vehicles will not negatively impact an FPR score if the inspections are performed accurately. If vehicles that should fail their Smog Check inspection are getting passed, their higher-than-expected failure rate in follow-up inspections will hurt a FPR score.
Specific actions that can negatively affect a FPR score include:
- Incorrect gear selection
- Over-conditioning vehicles
- Not identifying visual inspection failures
- Not identifying functional inspection failures such as fuel cap, ignition timing, and low-pressure fuel evaporative emissions
- Entering incorrect vehicle parameters to generate more lenient emission standards
- Clearing OBD fault codes without performing necessary repairs
- Fraudulent activities such as clean plugging, clean gassing, or clean tanking.
Best practices to improve FPR scores
FPR scores can be improved by ensuring accurate Smog Check inspections are performed as outlined in the Smog Check Manual. Accurate Smog Check inspections, including thorough visual inspections and functional tests, take more time to perform. These times may be reduced if the inspector is experienced and familiar with the vehicle. Avoiding shortcuts and consistently performing high-quality inspections is key to achieving a high FPR score.
FPR score distribution
Beginning January 2025, FPR score distributions for stations and inspectors can be found in the monthly Smog Check Executive Summary Reports.
To learn more about STAR scores and criteria, go to STAR program.