If there are no diagnostic trouble codes, it should pass. If there is a problem with the emissions system, a check engine light should turn on.
Are they giving you any rationale for failure? The only thing I can think of is if the battery was disconnected or someone cleared codes. That would cause the monitors to indicate not ready (readiness). Basically, the system hasn't completed a component check yet. Thus, there could be a problem that the computer (PCM) hasn't recognized yet.
Additionally, the (EPA) guidelines allow one monitor "not ready" for 2001 or newer model year vehicles. So, if there is one monitor which is causing an issue, it can still be passed.
I hope this helps. Let me know if you have other questions.
Tuesday, November 2nd, 2021 AT 7:20 PM