Rejected: not ready to test

The Nevada DMV is emphatic about this one: a rejected test is not the same as a failed test. It is the OBD system saying it does not have enough information yet. Here is why it happens, how to avoid it, and what to do if it happens to you.

At a glance

• Not ready is not a fail; no repairs are needed (Nevada DMV).
• Common causes: a new or disconnected battery, or trouble codes cleared with a scanner.
• Fix: drive up to one week under varying conditions, city and highway.
• The DMV emissions lab can check readiness for free, no appointment, before 4:30 pm.

What the computer is waiting for

Every 1996 and newer car runs a set of self-checks on its emission systems as you drive. Technicians call them readiness monitors. Some finish in a few minutes; others need a particular mix of cold starts, steady highway cruising and stop-and-go before they complete. The OBD smog test looks to see that enough of them have finished. If they have not, the test cannot judge the car, and the result is rejected.

Why it happens

The DMV names the usual suspects: the battery was recently disconnected or replaced, or the codes were cleared. Either one wipes the computer's memory and resets the monitors to unfinished. The DMV also warns that using a scanner to erase trouble codes right before a test results in an automatic rejection, because clearing codes erases what the inspector needs to see.

That is why the DMV's advice after a repair or a battery replacement is not to rush to get tested. Even if the check engine light is off, the system may show rejected.

How to get ready

Drive the vehicle for up to one week under varying conditions, city and highway, then return for the test. A normal week of commuting and errands usually does it. There is nothing to repair and nothing to buy.

The free readiness check

If you want to know before you come back, the DMV says your local emission lab can check whether the vehicle is ready to be tested at no cost. No appointment is needed, but arrive before 4:30 p.m. The Reno lab is at 9155 Double Diamond Pkwy, (775) 684-3580.

When the deadline is close

If the registration is about to expire while you are driving the monitors back to ready, the DMV offers a movement permit so you can stay legal on the road. It is one more reason the DMV recommends testing early: a not ready result with plenty of time left is a non-event.

Avoiding it next year

If the battery dies or gets replaced in the weeks before your renewal, plan the test for a week or so later. The same goes for any repair that clears codes. Testing early in the 90-day window gives you room to drive the monitors back to ready without the deadline pressing.

And never clear the check engine light with a code reader just before the test. The DMV treats that as an automatic rejection, and the light will come back anyway if the fault is still there.