--- title: Readiness Monitors, in Plain English | Xpress Smog url: https://xpresssmogcenter.com/guides/readiness-monitors/ business: Xpress Smog Check Center (Located inside Xpress Oil & Lube Center) locations: Reno Northwest: 6100 Mae Anne Ave, Reno, NV 89523, (775) 787-1000, Mon-Fri 8 am-5 pm, Sat 8 am-4 pm, Sun closed; Reno South: 4993 Longley Ln, Reno, NV 89502, (775) 828-6996, Mon-Fri 8 am-5 pm, Sat 8 am-3 pm, Sun closed type: Nevada smog check (vehicle emissions inspection), drive in, no appointment --- Located inside Xpress Oil & Lube Center - Smog check at two Reno locations - Oil change in the same visit - No appointment needed [Xpress Oil & Lube](https://xpressoilandlube.com/) - [Home](https://xpresssmogcenter.com/) - [Guides](https://xpresssmogcenter.com/guides/) - Readiness monitors, in plain English # Readiness monitors, in plain English A readiness monitor is one of the self-checks a 1996 or newer car's computer runs on its emissions systems. When the checks have not all finished, usually after a battery disconnect or cleared codes, the smog test comes back rejected, or not ready, and the DMV says no repair is needed. 4.7 stars from 550 Google reviews of the two Reno Xpress Oil & Lube Centers Few results confuse drivers more than a rejected test on a car that seems fine. The word sounds like a fail, and it is not one. This guide explains what the computer is doing, why a recent repair or battery change sets it back, and how the Nevada DMV tells you to get through it. ## At a glance - Rejected (not ready) is not a failure, according to the Nevada DMV. - The usual causes are a recently disconnected battery or recently cleared codes. - The DMV's fix is to drive up to one week under varying conditions, city and highway, then retest. - The Reno emission lab can check readiness at no cost, no appointment, if you arrive before 4:30 p.m. ## What the computer is doing Every light-duty vehicle built in 1996 or later carries the on-board diagnostics system known as OBD II. The DMV describes it as a standardized computer system that continuously monitors the engine's performance and the emissions control systems. When a sensor detects a malfunction, the computer stores a diagnostic trouble code and turns on the check engine light. Monitoring is not instant, though. The computer has to see the engine run through real driving before it can finish its checks, and the DMV's wording is that the system must complete all its checks under varying conditions. Those checks are what people mean by readiness monitors. ## Why a reset sets the clock back The result of the checks lives in the computer's memory. Disconnect the battery, replace it, or erase codes with a scan tool and that memory is cleared. The computer starts over, and until the checks are done again the car reports that it is not ready to be tested. The DMV lists the same two triggers every time it explains this: the battery was recently disconnected, or codes were cleared. It adds a related warning to not test immediately after a battery change, because a dead, disconnected or newly replaced battery clears the computer's memory. ## A rejection is not a fail On the DMV's pages the two words are kept apart on purpose. A failed test means the car is emitting too much, or the check engine light is lit. A rejected test only means the vehicle is not ready to be tested. The rejection costs you a return trip, not a repair bill, and it does not count as the failed test that starts the waiver process. If you were rejected right after a repair, the repair may be fine. The car simply has not been driven enough since it was done. ## How to get a car ready again The DMV's instruction has two parts. First, drive the vehicle for up to one week under varying conditions, both city and highway. Second, return for a retest. Think of it as a week of ordinary errands rather than one long trip: cold starts, stop and go traffic, steady speeds on the freeway. The DMV also offers a shortcut. After a rejected result, your local emission lab can check whether your 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 and answers at (775) 684-3580, and our [emissions lab guide](https://xpresssmogcenter.com/guides/dmv-emissions-lab-reno/) covers when a trip there makes sense. ## What not to do Do not clear the codes to make a light disappear before the test. The DMV is blunt that using a scanner to erase trouble codes right before a test produces an automatic rejection, since clearing does not fix the problem and only erases the memory the inspector needs to see. Also avoid scheduling the test for the day after a repair or battery replacement. If the registration deadline is close, ask about the timing, and read about the [movement permit](https://xpresssmogcenter.com/guides/movement-permit/) as a backstop. ## Where it fits in a normal year For most cars nothing here ever comes up. The computer finishes its checks during normal driving and the test runs in the five minutes or less the DMV quotes for OBD tests. Readiness only becomes a topic after something interrupts the computer, which is why recent work on the car belongs in the first thing you say at the counter. See [the not ready page](https://xpresssmogcenter.com/smog-check/not-ready-rejected/) for the short version. ### Sources - [dmv.nv.gov/emission_obd.htm](https://dmv.nv.gov/emission_obd.htm) (Nevada DMV On-Board Diagnostics page; read 10/19/26) - [dmv.nv.gov/emission.htm](https://dmv.nv.gov/emission.htm) (Nevada DMV Emission Control Program: testing areas, exemptions, validity; read 10/19/26) - [dmv.nv.gov/emission_diesel.htm](https://dmv.nv.gov/emission_diesel.htm) (Nevada DMV emission pages: Reno Emission Lab address; read 10/19/26) ### Your location: Reno South - Call [(775) 828-6996](tel:+17758286996) Mon-Fri 8 am-5 pm, Sat 8 am-3 pm, Sun closed - Address 4993 Longley Ln, Reno, NV 89502 [Directions](https://www.google.com/maps/dir/?api=1&destination=4993+Longley+Ln%2C+Reno%2C+NV+89502&destination_place_id=ChIJc5xNCcI_mYARXjHn3y79iJw) Located inside Xpress Oil & Lube Center Both smog check locations sit inside an Xpress Oil & Lube Center, the locally owned Reno drive-in that has served this town since 1983. Drive in, no appointment; get your oil changed in the same visit. [About us](https://xpresssmogcenter.com/about/) ### Keep reading - [Rejected: not ready to test](https://xpresssmogcenter.com/smog-check/not-ready-rejected/) - [Not ready and rejected results](https://xpresssmogcenter.com/faq/not-ready-questions/) - [After a battery change or a repair](https://xpresssmogcenter.com/faq/battery-and-recent-repairs/) - [How to give your car its best chance to pass](https://xpresssmogcenter.com/guides/pass-your-smog-check/) - [The DMV emissions lab in Reno: when to go there](https://xpresssmogcenter.com/guides/dmv-emissions-lab-reno/) ## Questions people ask Still have a question? Call either Reno location or just drive in; there is no appointment to make. ### Does a rejected test count against me? The DMV treats it as a different result from a failure and says no repair is needed. It only means the car must be driven and retested. ### How long does it take to become ready? The DMV says up to one week of varying driving. The exact time depends on the car and how it is driven. ### Can I pay a shop to force it ready? The DMV's guidance is driving, not shortcuts. Clearing codes to try to cheat the test ends in an automatic rejection.