--- title: P0440 and Your Nevada Smog Check | Xpress Smog Check Center url: https://xpresssmogcenter.com/codes/p0440/ 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/) - [Codes](https://xpresssmogcenter.com/codes/) - P0440 # P0440 and your Nevada smog check P0440 means the engine computer found a problem in the evaporative emission (EVAP) system, which traps gasoline vapor from the fuel tank so it does not escape into the air. It turns on the check engine light, so a 1996 or newer light-duty vehicle fails its Nevada smog check until the fault is fixed and the light is off. 4.7 stars from 550 Google reviews of the two Reno Xpress Oil & Lube Centers Gasoline vapor is pollution you cannot see. The EVAP system catches it in a charcoal canister and later feeds it to the engine to burn. P0440 is the broad, catch-all EVAP code: something in that sealed system is not behaving the way the computer expects. Before anything else, check the simplest part, the gas cap. ## At a glance - SAE J2012 meaning: Evaporative emission system malfunction. - The Nevada DMV names a loose gas cap as a common cause when the light comes on suddenly. - A lit check engine light fails 1996 and newer light-duty vehicles in Nevada. - The EVAP monitor can take some driving to finish after codes are cleared. ## First, the gas cap If the light came on soon after a fill-up, the DMV's advice is to check the gas cap. A loose or broken cap is one of the most common reasons the light comes on suddenly. Tighten it until it clicks and drive normally. The DMV notes the light may go off on its own after a few days of driving once the problem is resolved, so do this well before test day rather than on the way in. A cracked seal or a cap that will not click is worth replacing. If the light stays on after that, the problem is elsewhere in the system. ## What the EVAP system is SAE J2012 gives P0440 the generic name "Evaporative emission system malfunction." The system is a set of sealed lines from the fuel tank to a charcoal canister, with a purge valve that lets the engine draw stored vapor in to burn and a vent valve that lets fresh air in. The computer periodically tests the system for leaks and proper operation, often by sealing it and watching pressure or vacuum. Many vehicles set a more specific EVAP code, such as a small, large or very small leak. P0440 is the general one the computer uses when it sees a fault it does not pin down further. ## What it means at the test Nevada's OBD inspection reads the computer through the diagnostic port; no probe goes in the tailpipe. A lit lamp is an automatic fail. An EVAP code fails the test just as a misfire would, even though the car drives perfectly, because the rule is about the lamp. The DMV suggests testing anyway so you have the failed report. It documents why the vehicle failed, starts the waiver process if repairs get costly, and supports a reduced-cost ten-day movement permit if registration has lapsed. ## Common causes a repair shop checks Common causes a repair shop checks are listed above. Finding a vapor leak usually takes shop equipment. - A loose, damaged or wrong gas cap, or a worn filler neck seal. - Cracked or disconnected EVAP hoses and lines. - A purge valve or vent valve that sticks or has a circuit fault. - A damaged charcoal canister. - A leak at the fuel tank or its fittings. ## Timing the retest The EVAP self-check is often the slowest to finish, because many vehicles run it only under certain conditions, such as particular fuel levels and a cold start. After a repair clears the codes, follow the DMV's guidance: drive up to one week under varying conditions, city and highway, then retest. The DMV is clear that clearing codes right before a test brings an automatic rejection. Our [readiness monitor guide](https://xpresssmogcenter.com/guides/readiness-monitors/) explains why. Testing early in your 90-day window leaves room for this. A passing test is good for 90 days for a renewal. ## When repairs are not enough If the vehicle still fails after repairs, Washoe County's waiver path asks for receipts of at least $200 in parts and labor at a 2G licensed authorized station for repairs directly related to the failure, or at least $200 in related parts the owner bought within 14 days after the initial test, then a trip to the DMV Emission Lab with both failed certificates. Check emissions warranty coverage or a recall with the dealer before paying; federal law covers some costly emission components up to 8 years or 80,000 miles. ### Sources - [dmv.nv.gov/emission.htm](https://dmv.nv.gov/emission.htm) (Nevada DMV Emission Control Program: loose gas cap tip, waivers, 90-day validity; read 11/3/26) - [dmv.nv.gov/emission_obd.htm](https://dmv.nv.gov/emission_obd.htm) (Nevada DMV OBD page: light on is a fail, cleared codes rejected, federal emissions warranty; read 11/3/26) - [obd-codes.com/p0440](https://www.obd-codes.com/p0440) (public code reference for the P0440 definition; read 11/3/26) ### P0440, the generic definition Evaporative emission system malfunction The SAE J2012 code title. The same P0 code means the same thing on every 1996 and newer OBD II vehicle; the cause behind it differs car to car. ### 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) ### Related - [Check engine codes](https://xpresssmogcenter.com/codes/) - [P0446 and your Nevada smog check](https://xpresssmogcenter.com/codes/p0446/) - [P0455 and your Nevada smog check](https://xpresssmogcenter.com/codes/p0455/) - [P0442 and your Nevada smog check](https://xpresssmogcenter.com/codes/p0442/) - [Check engine light and your smog check](https://xpresssmogcenter.com/smog-check/check-engine-light/) - [Repair and retest](https://xpresssmogcenter.com/smog-check/repair-and-retest/) 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/) ## More evaporative emission (evap) system codes [P0455 Evaporative emission system leak detected (large leak) Learn more](https://xpresssmogcenter.com/codes/p0455/)[P0442 Evaporative emission system leak detected (small leak) Learn more](https://xpresssmogcenter.com/codes/p0442/)[P0456 Evaporative emission system leak detected (very small leak) Learn more](https://xpresssmogcenter.com/codes/p0456/)[P0441 Evaporative emission system incorrect purge flow Learn more](https://xpresssmogcenter.com/codes/p0441/)[P0446 Evaporative emission system vent control circuit Learn more](https://xpresssmogcenter.com/codes/p0446/) ## If the light is on at your smog check [### Check engine light and your smog check Why a lit check engine light decides the test. Learn more](https://xpresssmogcenter.com/smog-check/check-engine-light/)[### Failed a smog check What the failed report means and the steps that follow. Learn more](https://xpresssmogcenter.com/smog-check/failed-smog-check/)[### Repair and retest Getting the repair done and coming back for the second test. Learn more](https://xpresssmogcenter.com/smog-check/repair-and-retest/)[### Rejected: not ready to test Why a car can be turned away without failing. Learn more](https://xpresssmogcenter.com/smog-check/not-ready-rejected/) ## P0440 questions Still have a question? Call either Reno location or just drive in; there is no appointment to make. ### I tightened the cap. Why is the light still on? The DMV says the light may take a few days of normal driving to go off once the problem is fixed. If it stays on longer, the cause is likely elsewhere. ### Can I test right after the light goes off? If the light went off on its own, the monitors may already be complete. If the codes were cleared with a scanner, expect a not ready result until the car has been driven. ### How is P0440 different from P0455? P0455 is a specific large-leak code. See our [P0455 page](https://xpresssmogcenter.com/codes/p0455/).