--- title: P0133 and Your Nevada Smog Check | Xpress Smog Check Center url: https://xpresssmogcenter.com/codes/p0133/ 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/) - P0133 # P0133 and your Nevada smog check P0133 means the oxygen sensor ahead of the catalytic converter on bank 1 is switching between rich and lean readings more slowly than the engine computer expects. The code lights the check engine light, and with the light on a 1996 or newer light-duty vehicle fails its Nevada smog check. 4.7 stars from 550 Google reviews of the two Reno Xpress Oil & Lube Centers Technicians sometimes call this a lazy sensor. The part still works, just not fast enough for the computer to trust it. Because the upstream sensor steers the fuel mixture, a slow one matters to emissions, and the OBD II system flags it. This page covers what the code means, why it fails the test in Washoe County, and the steps that keep your registration on track. ## At a glance - SAE J2012 definition: O2 sensor circuit slow response (bank 1, sensor 1). - A slow upstream sensor makes fuel control less precise, which can raise emissions. - A lit check engine light is an automatic fail on 1996 and newer light-duty vehicles (DMV). - A failed report is useful: it starts the repair, retest and waiver path. ## Fast switching is the whole point The generic name in the SAE J2012 list is "O2 sensor circuit slow response (bank 1, sensor 1)." A healthy upstream oxygen sensor flips its signal back and forth many times as the engine computer trims the fuel slightly rich, then slightly lean, around the ideal mixture. That constant correction is what lets the catalytic converter clean the exhaust efficiently. As a sensor ages or gets contaminated, it reacts more slowly. The computer times how long the signal takes to swing, and when the response falls outside its limit it stores P0133. Bank 1 is the side with cylinder one, and sensor 1 is the one before the converter. ## How it shows up for the driver Often it does not show up at all, apart from the lamp. Some drivers notice lower fuel economy over time, or an engine that feels slightly less crisp after a cold start. The Nevada DMV makes the general point that a car with the check engine light on is likely wasting fuel and polluting even if it feels normal, and P0133 fits that description well. ## Common causes a repair shop checks A slow sensor is the obvious suspect, but the code can have other roots. Common causes a repair shop checks include: - An oxygen sensor that has simply aged. - Sensor contamination, for example from coolant or oil getting into the combustion chamber. - An exhaust leak near the sensor that lets outside air dilute the reading. - Wiring or connector problems in the sensor circuit. - An intake air leak that upsets the mixture the sensor is trying to report. ## The Washoe County test with P0133 stored The OBD test reads the computer, not the exhaust. A technician scans the VIN bar code, plugs into the diagnostic port and the analyzer records the result, which reaches the DMV in real time. With the lamp lit, it is a fail. Come in anyway if your renewal is near. The DMV calls the failed test a legal document showing why the vehicle fails, and it is the gate to a reduced-cost ten-day movement permit when registration has expired, to a challenge test at the emissions lab, and to the waiver process. One caution from the DMV: repairs paid for before that first failed test do not count toward a waiver. ## Repair, drive, retest Once a repair shop has done the work, the codes are usually cleared, and that resets the readiness monitors. The DMV describes a rejected, not ready result as no failure at all, just a computer that has not finished its checks. Its advice is to drive up to one week under varying conditions, city and highway, then return for the retest. See [not ready and rejected](https://xpresssmogcenter.com/smog-check/not-ready-rejected/) for more. If the vehicle still fails after repairs, a Washoe waiver may be possible: receipts of at least $200 for directly related repairs at a 2G licensed authorized station, or at least $200 for related parts the owner bought within 14 days after the initial test. The vehicle, both failed certificates and the receipts then go to the DMV Emission Lab. ## Is the sensor covered Federal law covers some expensive emission components for up to 8 years or 80,000 miles, and the DMV says to check with the dealer about emissions warranty coverage or a recall before you pay. Ask about the specific part and your mileage. ### Sources - [dmv.nv.gov/emission_obd.htm](https://dmv.nv.gov/emission_obd.htm) (Nevada DMV OBD page: light on means fail, test anyway, rejected not ready, federal emissions warranty; read 11/3/26) - [dmv.nv.gov/regrenewal.htm](https://dmv.nv.gov/regrenewal.htm) (Nevada DMV: Washoe waiver receipts and the Emission Lab; read 11/3/26) - [obd-codes.com/p0133](https://www.obd-codes.com/p0133) (public code reference for the P0133 definition; read 11/3/26) ### P0133, the generic definition O2 sensor circuit slow response (bank 1, sensor 1) 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/) - [P0135 and your Nevada smog check](https://xpresssmogcenter.com/codes/p0135/) - [P0171 and your Nevada smog check](https://xpresssmogcenter.com/codes/p0171/) - [P0420 and your Nevada smog check](https://xpresssmogcenter.com/codes/p0420/) - [Rejected: not ready to test](https://xpresssmogcenter.com/smog-check/not-ready-rejected/) - [Smog waiver in Washoe County](https://xpresssmogcenter.com/smog-check/smog-waiver/) 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 oxygen sensors codes [P0135 O2 sensor heater circuit (bank 1, sensor 1) Learn more](https://xpresssmogcenter.com/codes/p0135/)[P0141 O2 sensor heater circuit (bank 1, sensor 2) Learn more](https://xpresssmogcenter.com/codes/p0141/) ## 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/) ## P0133 questions Still have a question? Call either Reno location or just drive in; there is no appointment to make. ### Is P0133 serious? It is not the flashing-light kind of problem the DMV says to stop for. It does fail the Nevada smog check while the lamp is lit, and it can cost fuel over time. ### Can a bad sensor damage the converter? A mixture that stays off target can work the converter harder over time. A repair shop can tell you whether that applies to your car. ### How is this different from P0135? P0135 is the heater circuit of the same sensor. P0133 is about how fast the sensor's signal responds. See our [P0135 page](https://xpresssmogcenter.com/codes/p0135/).