TX inspection rejection guide · Glass Box Diagnostics
The OBD port doesn't just store fault codes; it reports whether the car's own emission self-tests (readiness monitors) have completed since the last clear. If someone reset the ECU to hide a light before inspection, the car shows 'not ready' and fails the OBD check even with no faults present. This is the most annoying failure in the program because the fix can be nothing more than driving the car correctly — but it is also the moment to make sure there's no real fault waiting underneath, because once the monitors finish, the light can come back on.
The clock: A drive cycle can take 3–7 days of normal use; some monitors only set after a full cool soak overnight. If the slip clock is short, book now — a scan that finds a pending code hiding under the clear saves you a second round entirely.
Either shrug and say 'drive it and come back' with no scan — or worse, 'module needs reprogramming, $900' — while a pending code they never looked for sits in memory ready to relight the CEL after your re-inspection.
Typical guess-and-swap cost: $800–$1,200 in 'reprogramming' for a car that only needed a scan and a week of driving
Readiness status per monitor, pending (not just confirmed) codes, and freeze frames — ten minutes on a factory-level scan tool tells you whether this is 'go drive it' or 'there's a fault preventing the test from completing.'
Codes behind this rejection
We come to you — Canyon Lake, San Antonio & Austin. Written report naming the root cause — see a sample. Already have a repair quote? Run it through the numbers.