# P0500: Vehicle Speed Sensor "A" **Verdict:** Drive to a shop this week Speed and idle control - Generic OBD-II code, applies to all gasoline cars and light trucks sold in the US since 1996. - **Typical cost:** $120-$500 - **Urgency:** This week - **Most likely:** Failed vehicle speed sensor or wiring - **DIY?:** Sometimes, if easy to reach ## Quick answer P0500 means the engine or transmission computer is not getting a believable vehicle speed signal from speed sensor "A". Many systems depend on this signal, so you may see a dead or erratic speedometer, harsh or odd shifting, and cruise control that will not work. A failed speed sensor or damaged wiring is the usual cause. ## What does P0500 mean? The vehicle speed sensor tells the engine and transmission computers how fast the car is moving. On older cars it is usually a magnetic sensor on the transmission or rear axle that reads a toothed wheel or a small drive gear. On many newer cars there is no separate sensor, and the computers calculate vehicle speed from the ABS wheel speed sensors instead. P0500 sets when the computer sees no speed signal, or a signal that makes no sense, while other data says the car must be moving, such as the transmission in gear with high engine speed and load. Sensor "A" simply means the first or main speed sensor in the maker's design. The exact conditions and timing vary by maker, and on some cars the check engine light comes on after one failed trip, while on others it takes two. ## What are the symptoms of P0500? - Speedometer reads zero, jumps around, or works only sometimes - Harsh, late, or erratic transmission shifts - Cruise control does not work - ABS or traction control light on in some cars - Check engine light on ## What causes P0500? Ranked from most to least likely. Check them in this order: the cheap, common causes first. 1. **Failed vehicle speed sensor** (most common). Magnetic speed sensors sit in a harsh spot on the transmission or rear axle, exposed to heat and vibration, and their internal coil can open up or weaken with age. Metal particles in the fluid can also coat the magnetic tip and blur the signal. A speedometer that suddenly drops to zero while driving is a strong clue. 2. **Damaged wiring or connector** (common). The sensor wiring runs low on the vehicle, near hot exhaust parts and in the path of road spray, salt, and debris. Chafed insulation, corroded connector pins, or a wire pulled loose during other repairs can interrupt the signal, often only over bumps. A speedometer that cuts out on and off, especially in wet weather, often points to wiring. 3. **Faulty ABS wheel speed sensor (on cars that use wheel speed)** (common). Many newer vehicles calculate vehicle speed from the ABS wheel speed sensors, so one failed wheel sensor or a damaged sensor wire can set P0500 along with ABS codes. The ABS and traction control lights usually come on as well. Rust building up under the sensor and damage during brake work are common triggers. 4. **Damaged sensor drive gear or tone ring** (less common). Older transmission-mounted sensors are often turned by a small plastic drive gear that can strip its teeth, while axle and wheel sensors read a toothed tone ring that can crack or rust. Either way the sensor itself works but sees an incomplete pattern. It usually shows up on higher-mileage vehicles or after axle or wheel bearing work. 5. **Instrument cluster or computer fault** (rare). Occasionally the instrument cluster or a control module that receives and shares the speed signal fails internally, or its connector works loose. This is rare and is only considered after the sensor, its wiring, and any ABS sensors test good. A shop may also check whether other modules on the car's network can see the speed signal. ## How do you diagnose P0500? 1. Read all codes, including ABS codes, since many cars share speed signals between systems. 2. Check the vehicle speed reading on a scan tool while driving, and compare with GPS speed. 3. Locate and inspect the speed sensor and its wiring and connector. 4. Test the sensor's output signal with a scope or meter while turning the wheels. ## How do you fix P0500, and what does it cost? | Fix | Typical cost | What it involves | | --- | --- | --- | | Replace vehicle speed sensor | $120-$350 | Usually bolts into the transmission or axle housing. | | Replace ABS wheel speed sensor | $150-$400 | For vehicles that use wheel speed as the vehicle speed signal. | | Repair wiring or connector | $100-$300 | Fixes chafed wires or corroded pins. | ## Is it safe to drive with P0500? > **Drive to a shop this week.** The car is usually drivable, but without a working speedometer you can easily speed, and odd shifting or disabled ABS reduce safety. Get it repaired soon. ## Will P0500 fail an emissions test? With the check engine light on, P0500 fails an OBD-II emissions test in most states. A missing speed signal can also stop some readiness monitors from finishing, because tests such as the catalyst and oxygen sensor monitors often need steady cruising at a known speed. Repair the sensor, then drive normally until the monitors complete. ## After the repair: clearing P0500 After the repair, clear codes from the engine computer and, if the car shares speed signals, from the ABS module too. Test drive and check that the speedometer reads steadily and matches a GPS app, that shifts feel normal, and that cruise control works. If the code stays away for several drive cycles and the monitors complete, the fix held. ## How to prevent P0500 - Have wiring near the wheels and transmission checked after off-road driving or hitting road debris. - Change transmission fluid on schedule to limit metal particles that collect on magnetic speed sensors. - Ask the shop to put sensor wires back in their clips after brake, axle, or suspension work. - In road-salt states, rinse the underbody during winter to slow corrosion of sensor connectors. - Fix transmission or axle fluid leaks promptly so oil does not soak into sensor connectors. ## Codes often seen with P0500 - [P0700](/codes/p0700): Transmission Control System (MIL Request) - [P0715](/codes/p0715): Input/Turbine Speed Sensor "A" Circuit - [P0730](/codes/p0730): Incorrect Gear Ratio ## Frequently asked questions ### Can I drive with a P0500 code? You can drive carefully for a short time, but it is not ideal. A dead speedometer makes it easy to speed, the transmission may shift poorly, and ABS or traction control may be switched off. Use a phone GPS app to watch your speed, take extra care in bad weather, and get it repaired soon. ### Can a bad speed sensor affect shifting? Yes, automatic transmissions use vehicle speed to decide when to shift and when to lock the torque converter. A bad signal can cause harsh, late, or erratic shifts, or put the transmission in a backup mode that holds one gear. Shifting usually returns to normal once the speed signal is repaired. ### Where is the vehicle speed sensor? It is usually on the transmission case near the output shaft, or on the rear axle housing of many rear-wheel-drive trucks. Many newer cars have no separate sensor and use the ABS wheel speed sensors instead. A service manual or parts catalog for your exact vehicle shows which type you have and where it sits. ### How much does it cost to fix P0500? Most P0500 repairs cost $120 to $500. A transmission-mounted speed sensor usually costs $120 to $350 installed, an ABS wheel speed sensor $150 to $400, and a wiring or connector repair $100 to $300. Diagnostic time can add to the bill if the fault comes and goes and is hard to catch. ### Can I replace the vehicle speed sensor myself? Often, if the sensor is easy to reach. Many bolt into the transmission or axle with a single bolt and one connector, and a little fluid may drip out when you remove it. Confirm the diagnosis first, because a wiring fault or a failed ABS sensor will not be fixed by a new transmission sensor. ### Why did my speedometer stop working? A failed vehicle speed sensor or its wiring is the most common reason, especially when P0500 is stored. A bad ABS wheel sensor or a stripped drive gear can also do it. If the speedometer dies but no P0500 or ABS codes are stored, the instrument cluster becomes a stronger suspect. ### Will P0500 fail an emissions test? Yes, in most states a lit check engine light with P0500 stored fails an OBD-II emissions test. The missing speed signal can also keep some readiness monitors from completing, because they need steady driving at a known speed. Fix the sensor and drive normally for several days before going in for the test. ### Can P0500 make the ABS light come on? Yes, on many vehicles. When vehicle speed comes from the ABS wheel sensors, a failed wheel sensor sets both P0500 and an ABS code, and the ABS and traction control lights come on together. In that case, anti-lock braking may be switched off until the repair is made, so brake gently on slippery roads. ### Why does my cruise control not work with P0500? Cruise control needs a steady vehicle speed signal to hold your speed, so the computer switches it off when that signal is missing or erratic. This is a safety feature rather than a separate fault. Cruise control usually works again as soon as the speed sensor or its wiring is repaired. ### Can dirty transmission fluid cause P0500? Not usually, but it can contribute. Transmission-mounted speed sensors are often magnetic, and metal particles in old fluid can collect on the tip and weaken the signal. If the sensor comes out coated in debris, the shop may recommend a fluid service and a check of the transmission for wear. ## Sources - [SAE J2012: Diagnostic Trouble Code Definitions](https://www.sae.org/standards/content/j2012_201812/) ## Other speed and idle control codes - [P0505 Idle Air Control System](https://diagxcar.com/codes/p0505) - [P0506 Idle Air Control System RPM Lower Than Expected](https://diagxcar.com/codes/p0506) - [P0507 Idle Air Control System RPM Higher Than Expected](https://diagxcar.com/codes/p0507) - [P0520 Engine Oil Pressure Sensor/Switch "A" Circuit](https://diagxcar.com/codes/p0520) - [P0521 Engine Oil Pressure Sensor/Switch "A" Circuit Range/Performance](https://diagxcar.com/codes/p0521) - [P0522 Engine Oil Pressure Sensor/Switch "A" Circuit Low](https://diagxcar.com/codes/p0522) - [P0523 Engine Oil Pressure Sensor/Switch "A" Circuit High](https://diagxcar.com/codes/p0523) - [P0524 Engine Oil Pressure Too Low](https://diagxcar.com/codes/p0524) - [P0562 System Voltage Low](https://diagxcar.com/codes/p0562) - [P0571 Brake Switch "A" Circuit](https://diagxcar.com/codes/p0571) - [P0700 Transmission Control System (MIL Request)](https://diagxcar.com/codes/p0700) - [P0715 Input/Turbine Speed Sensor "A" Circuit](https://diagxcar.com/codes/p0715) - [P0720 Output Shaft Speed Sensor "A" Circuit](https://diagxcar.com/codes/p0720) - [P0730 Incorrect Gear Ratio](https://diagxcar.com/codes/p0730) ## Warning lights linked to this - [ABS warning light](https://diagxcar.com/warning-lights/abs) - [Traction control light](https://diagxcar.com/warning-lights/traction-control) --- Source page: https://diagxcar.com/codes/p0500 Updated: 2026-11-03 General information, not a substitute for a qualified mechanic.