Why would a dead battery cause my vehicle to fail State inspection?
In States with mandatory emissions testing, vehicles from 1996 and up have to pass the on board diagnostics or OBD test. Failures and pass/fail test results are stored in the vehicle computer. When the battery is disconnected or dies these results are loss, causing an inspection failure. When the battery is replaced, the tests will begin to run. Running readiness-tests can take up to several days driving. The vehicle will fail inspection until the tests are successfully completed. For even more information on check engine lights, see our Detailed Topics article, Failing State Inspection.
