TransmissionGeneric OBD-II codeUrgency: Garage soon
Code P0720: automatic gearbox output speed sensor
P0720 means: output speed sensor circuit fault (from the gearbox output shaft).[1][2][3] The gearbox control unit (or the engine control unit) expects to receive a valid speed signal from the sensor on the gearbox output shaft and does not receive it, or receives it intermittently or with errors. It uses that signal to decide when to change gear, so without it the gearbox cannot shift properly. In practice, TroubleCodes.net refers to the signal from the output shaft sensor or the vehicle speed sensor (VSS).[1][2][3]
What code P0720 means
The gearbox control unit (or the engine control unit) expects to receive a valid speed signal from the sensor on the gearbox output shaft and does not receive it, or receives it intermittently or with errors. It uses that signal to decide when to change gear, so without it the gearbox cannot shift properly. In practice, TroubleCodes.net refers to the signal from the output shaft sensor or the vehicle speed sensor (VSS).[1][2][3]
According to AutoDTCs, the code is stored when the signal is missing or not credible when moving forward, usually above about 10–15 km/h, and it typically requires no pulses for between 0.5 and 2 seconds with the accelerator pressed. The code does not say whether the fault is in the sensor, the tone wheel or the wiring.[1]
It should not be confused with P0715, which is the input (turbine) speed sensor of the gearbox: P0720 is the output shaft one. TroubleCodes.net notes that P0715 may be stored at the same time.[3]
Original definition (SAE J2012): Output Speed Sensor Circuit Malfunction[1][2][3]
Causes of P0720
From most to least likely, according to the sources.
- 1Faulty output speed sensor (or vehicle speed sensor). AutoDTCs identifies it as the most common cause.[1][2][3][4]
- 2Damaged, open or short-circuited wiring between the sensor and the control unit, or corroded or loose connectors.[1][2][3][4]
- 3Output shaft tone wheel damaged, corroded or with missing teeth.[1][2]
- 4Sensor loosely fitted or with a damaged tip, too much air gap; or sensor tip coated with contamination from the gearbox oil.[1]
- 5Low or contaminated gearbox oil.[2][4]
- 6Faulty input speed sensor or shift solenoids (CódigosDTC includes them among the causes).[2]
- 7Faulty control unit.[4]
Symptoms
- Engine fault warning light on.[1][2][3]Engine warning light: faults that cause it
- Speedometer that reads incorrectly or stops working (on some models).[1][2][3][4]
- Poor shifts: gears skipped, late upshifts or upshifts that do not happen, and hesitation when downshifting.[1][2][3]Gears will not engage: faults that cause it
- Limp mode with gears restricted.[1][4]Limp mode: faults that cause it
- Torque converter does not lock at motorway speed (AutoDTCs); ABS and stability control warning lights on some models.[1]
- Worse fuel consumption.[3]Uses more fuel: faults that cause it
How to diagnose P0720
In order: from the most likely and cheapest to check to the most expensive.
- 1Check the output speed in the live data of the diagnostic equipment while driving above 15 km/h: a reading of zero while moving confirms the signal is missing. Compare it with the speedometer if possible.[1]
- 2Inspect the sensor and its connector: corrosion, damage and seating. Clean the sensor tip and check there is no debris between it and the tone wheel.[1][2]
- 3Check the wiring and connectors between the sensor and the control unit: continuity, short circuits to earth, loose or dirty connections, and move the harness to see whether the reading changes.[1][2]
- 4With the sensor disconnected, measure its resistance and compare it with the manufacturer's figure. AutoDTCs cites about 200 to 2,000 ohms for passive sensors and, for Hall-effect sensors, the supply voltage and the signal switching as the wheel turns.[1][2]
- 5Check the level and condition of the gearbox oil and the hydraulics.[2][4]
- 6If the sensor and wiring are good and the code persists, inspect the tone wheel (this may require draining the oil or removing the sump or the extension housing). Before replacing the control unit, check its power supply and earth.[1][2]
Can I keep driving with P0720?
Garage soon
AutoDTCs rates it as high severity: gearbox control is severely degraded, with incorrect shifts and possible limp mode, and it recommends limiting yourself to short, low-speed trips and avoiding the motorway until it is repaired. Rerev warns that, if left untreated, it can end in a gearbox failure and compromise driving safety, and asks for a workshop repair as soon as possible. The prudent course is not to make long journeys with the code active.[1][4]
Documented faults related to P0720
Known faults of specific engines and cars, with their repair cost, the affected years and their sources.
Automatic gearbox (torque converter and CVT): the most serious faults by engine and car
- Critical severityFrequency: CommonMultitronicWear of the variator chain and conesYes: the variator uses a chain of more than 1,000 links between two pairs of cones that wears with mileage, especially if the oil is not changed regularly. Gebrauchtwagenberater ties the gearbox's reputation to "numerous total failures"; Schaeffler/LuK sells a kit to repair the chain.
- Critical severityFrequency: Common2.0 CDI (OM640)Costly failure of the Autotronic (CVT) automatic gearboxYes: the Autotronic continuously variable gearbox, optional on the 180 CDI and 200 CDI, is the problem cited most by owners of the 140 hp version (24 of 114 testimonies) and a fault hotspot according to the ADAC up to 2006. A German source recommends avoiding it and choosing the manual gearbox.
- High severityFrequency: CommonMultitronicControl unit (TCU) failure and limp modeYes: the multitronic control unit, especially in the 01J code (up to 2007), is one of its best-documented weak points. Overheating with oil seeping into the control unit causes fault warnings and limp mode and, if ignored, can end up damaging the gearbox itself.
- High severityFrequency: Common7G-Tronic / 9G-TronicConductor plate and speed sensor failure (limp mode)Yes: one of the most cited weak points of the 7G-Tronic (722.9) is the internal conductor plate, which integrates the turbine, output and intermediate-shaft speed sensors; if it fails it can trigger a limp mode with delayed shifts or harsh jerks, although it does not always require replacing the whole gearbox.
- High severityFrequency: CommonAudi A6 C6Wear and failures of the Multitronic automatic gearbox on front-wheel-drive versionsYes: on front-wheel-drive versions with the Multitronic (CVT) gearbox, gebrauchtwagenberater.de documents jerking when pulling away that can progress to complete failure, especially on older cars; fiches-auto.fr adds selector lock-ups and torque converter breakages. The quattro versions, with the Tiptronic gearbox, do not share this problem.Repair (garage): €1,000Appears at around 120,000 km
- High severityFrequency: CommonMINI Cooper R50Faults in the CVT automatic gearbox, the manual gearbox and the clutchAccording to the reports collected by fiches-auto.fr, the Mini R50 accumulates 22 gearbox mentions and 32 clutch mentions, and the CVT automatic variant is described as fragile and 'to be avoided'. Wikipedia confirms that the CVT and the manual gearboxes were fitted depending on the year.
Wiring, connectors and short circuits: the most serious faults by engine and car
- Critical severityFrequency: OccasionalBMW N62 / N63Additional turbo coolant pump with a risk of short circuit and fireIn 2011 BMW recalled 5, 6 and 7 Series, X5 and X6 models built between 2007 and 2011 because of the additional turbo coolant pump: moisture, a short circuit and, in extreme cases, a fire. In 2012 there was another campaign for a crack in the pump, with a more robust version.
- Critical severityFrequency: Occasional1.6 GDi híbrido (Kappa)Main relay of the power relay assembly (overheating and fire risk)Yes, on the first units: Hyundai and Kia recalled 2016–2018 Ioniq and Niro hybrids and plug-in hybrids because the main relay that connects the high-voltage battery could come loose, overheat and, in the worst case, cause a fire.
- Critical severityFrequency: Occasional1.6 GDi híbrido (Kappa)Clutch hydraulic actuator (HCA): leak or moisture with risk of short circuit and fireYes, this is the most documented hybrid system fault: the hydraulic actuator that engages the combustion engine with the hybrid assembly has had two recalls (2018 for a leak on the Niro and 2025 for moisture in its electronic board on the Niro, Ceed and XCeed PHEV), with a risk of short circuit and fire.
- High severityFrequency: Occasional1.3 TCeBlown fuel pump fuseOn the Renault Captur II and Clio V with the 1.3 TCe engine, a 20-amp fuse can blow and leave the car without an engine. According to L'argus, in April 2021 this fault still had no factory fix; the official service centre's diagnosis includes checking, and sometimes replacing, the catalytic converter.
- Critical severityFrequency: CommonRover 75Seat SRS connector fault with airbag and seatbelt warning light onAuto Express warns that the Rover 75's seat SRS connector can cause the airbags to fail, and dealers were fixing it with revised connectors. The Dutch APK inspection puts the airbag or seatbelt fault warning among the most frequent defects across almost all series.
- Critical severityFrequency: OccasionalAlfa Romeo GiuliettaShort circuit from badly routed wiring that can prevent gear shifting (KBA campaign, 2010-2015)Yes: according to Germany's KBA, on Alfa Romeo Giulietta cars built between 2010 and 2015 inadequate cable routing could cause a short circuit and, as a result, gear-shift failure.
Control units and comfort electronics (BSI, SAM...): the most serious faults by engine and car
- High severityFrequency: CommonPeugeot 408Electronic faults with the doors, boot and screen (suspected BSI control unit)In 2025 Peugeot recalled around 60,000 2023-2024 Peugeot 308 and 408 cars (code MUV) over a software fault in the door control unit that can cause unintended opening or closing and disable the anti-trap protection on the windows; 408 owners also describe a power boot lid that will not open or close and a screen that goes black.
- High severityFrequency: CommonRenault Laguna IIMultiplex electrical system and hands-free card faultsThe Laguna II had a reputation problem because of faults in its multiplexed electrical network: the hands-free card, the card reader and the ABS, ESP and handbrake warning lights came on erratically, especially in the early years of production (2001-2003).
- Critical severityFrequency: OccasionalMazda MX-5 IVDC/DC converter control unit fault with risk of short circuit and fireA 2018 Safety Gate alert covers MX-5 ND models built between August 2014 and April 2017: the DC converter control unit could fail, cause a short circuit and damage the converter, with a risk of fire. It is a precautionary recall; check the chassis number at the official service centre.
- Medium severityFrequency: Very frequentFiat StiloElectrical and electronic faults in the multiplex systemThe Stilo has had a reputation for widespread electrical faults since its launch: poor contacts in the multiplex wiring, an instrument cluster that switches off and sensors that disconnect, sometimes while the car is running.
Frequently asked questions
Which sensor is the one for P0720?
The gearbox output speed sensor, which measures the rotation of the shaft that carries the drive to the wheels. According to TroubleCodes.net, the control unit may receive that signal from the output shaft sensor or the vehicle speed sensor. It is not the input (turbine) one, which has its own code.[2][3]
Why does the speedometer fail with P0720?
Because on many cars the displayed speed comes from the gearbox output shaft signal. AutoDTCs indicates that on some models the speedometer becomes inaccurate or stops working, and the other sources also cite this as a symptom.[1][2][3][4]
Is it the sensor or the tone wheel?
The code does not say. AutoDTCs recommends measuring the sensor and checking its wiring and connector, and only then inspecting the tone wheel, which may require draining the oil or removing the sump.[1]
Can I keep driving with P0720?
AutoDTCs advises limiting use to local, low-speed driving and avoiding the motorway until it is repaired, and Rerev asks for diagnosis and repair at a workshop as soon as possible. The reason is that the gearbox decides its gear changes with that signal.[1][4]
Will I pass the MOT with code P0720?
If the code has switched on the engine warning light, no: with that light on, the inspection records a serious defect, and on Euro 5 and Euro 6 cars the ITV (Spain's roadworthiness inspection, similar to the MOT) also reads the OBD diagnostic system. Repair the fault before you go; clearing the code just before the inspection does not help either, because it counts as a serious defect.[5]
Not sure what is wrong with your car? Describe what you notice in the symptom diagnosis or see all fault codes.
Sources
Every fact on this page links to its source. If you find an error, let us know.
- P0720 - Output Shaft Speed Sensor CircuitAutoDTCs · Technical documentation · consulted 31 October 2026
- P0720 - Error de circuito del sensor de velocidad de salidaCódigosDTC · Technical documentation · consulted 31 October 2026 · in Spanish
- P0720 trouble code - Output shaft speed (OSS) sensor circuit malfunctionTroubleCodes.net · Technical documentation · consulted 31 October 2026
- P0720 OBD2 codeRerev · Technical documentation · consulted 31 October 2026
- Desmontando mitos: ¿puede pasar mi coche la ITV con el testigo de «avería motor» encendido?Diariomotor · Motoring press · published 8 March 2021 · consulted 2 October 2026 · in Spanish