P0500 Code: Vehicle Speed Sensor A
The engine computer lost its vehicle speed signal – speedometer, shifting and cruise control may act up.
Safety first · Consult a professional
- Braking system affected: ABS may be disabled. Drive carefully and have it checked promptly.
At a glance
Severity: Moderate
- Meaning
- Vehicle Speed Sensor A
- System
- Speed & Idle Control · Powertrain
- Safe to drive?
- With caution
- Typical repair cost
- $0–$650
- DIY difficulty
- Moderate
Vehicle speed reaches the engine computer in one of two ways. Older cars and many trucks use a dedicated speed sensor on the transmission tailshaft, transfer case or rear differential that reads a toothed wheel. Most modern cars instead let the ABS module calculate speed from the wheel speed sensors and share it over the data network. P0500 sets when that signal is missing or its circuit is faulty while other data – engine rpm, load and gear – says the car is clearly moving. Because transmission shift timing, cruise control, idle strategy and often the speedometer depend on it, the symptoms are usually obvious right away.
Can I keep driving? Drive gently and only as far as needed. Shifts may be harsh or stuck in one gear, you can't trust the speedometer, and if the speed comes from the ABS system the ABS and traction control may be off – leave extra stopping distance.
How to read P0500
- P Powertrain
- 0 Generic (SAE)
- 5 Speed, idle & inputs
- 00 Specific fault
Symptoms
- Speedometer reads zero or drops out while driving
- Odometer stops counting miles
- Automatic transmission shifts harshly, late, or stays in one gear
- Cruise control won't engage
- ABS and traction control lights on (when speed comes from the ABS module)
- Engine may stall or dip when coming to a stop
Possible causes
Ranked by how often each cause is behind this code (editorial estimate).
- Failed dedicated vehicle speed sensor or transmission output speed sensor
- Wheel speed sensor or ABS module fault on cars that use ABS-derived speed
- Damaged wiring or connector near the transmission or axle
- Metal debris on a magnetic sensor tip or a damaged tone ring
- Instrument cluster or data network fault between modules
- Stripped speedometer drive gear on mechanically driven sensors
- Engine or transmission computer fault or wrong programming
Diagnosis step by step
Note the speedometer and ABS light
A dead speedometer together with an ABS or traction light usually means the speed signal comes from the ABS system and a wheel sensor is the problem. Scan the ABS module for codes such as C0035 before touching anything on the transmission.
Tools: OBD-II scanner
Compare every speed source
On a road test, log the vehicle speed PID, the four wheel speeds and the transmission output speed side by side. The one that drops to zero or never appears is your faulty circuit; if all wheel speeds are fine but the engine computer shows zero, suspect the network.
Tools: OBD-II scanner
Inspect and clean the sensor
Locate the sensor, check the connector for corrosion and the harness for rubbing on the exhaust or driveshaft. Remove a magnetic sensor and wipe off any metal fuzz on its tip, and check the O-ring for fluid leaks.
Tools: Flashlight, Screwdriver, Gloves
Test the sensor output
A two-wire magnetic sensor typically measures a few hundred to about 2,500 ohms and should produce an AC voltage that rises as the wheel or shaft turns faster. A three-wire Hall sensor needs a steady reference and ground, and its signal should switch cleanly on and off as the shaft rotates.
Tools: Multimeter
Check the wiring back to the module
With both ends unplugged, verify continuity of each wire and check for shorts to ground and to voltage. Pay attention to shielded cables, where a broken drain wire lets interference in.
Tools: Multimeter
Where the parts are
- 1Battery
- 2Alternator
- 3Engine computer (ECM)
- 4CAN bus
- 5Transmission
- 6Wheel speed sensor
- 7High-voltage battery
Repair options & costs
| Repair | DIY? | Estimated cost |
|---|---|---|
| Clean sensor tip and reseal | Yes | $0–$60 |
| Replace vehicle speed or output speed sensor | Yes | $100–$320 |
| Replace wheel speed sensor | No | $150–$400 |
| Repair sensor wiring or connector | No | $100–$350 |
| Replace tone ring or speedometer drive gear | No | $200–$650 |
Rough US estimates for parts and labor; shop rates vary by region. Not a quote.
Notes by brand
Ram
Many older Ram pickups read vehicle speed from a sensor on top of the rear differential. Metal debris on its magnetic tip, a weeping seal or a chafed wire near the axle commonly causes a dead speedometer, harsh shifting and P0500.
Field data
| Nissan | 4 | Quest, Maxima, Versa Note |
|---|
Source: NHTSA Complaints API (US government open data), analyzed by DTC mention.
Emissions / smog test impact
Will fail
P0500 lights the check engine light on most vehicles, so an OBD smog check fails. Speed-dependent monitors may also stay not ready until the repair is done and the car has been driven normally.
Frequently asked questions
Why do my ABS light and P0500 appear together?
On most modern cars the ABS module calculates vehicle speed from the wheel sensors and sends it to the engine and transmission computers. A failed wheel sensor therefore knocks out ABS and the speed signal at the same time.
Is it safe to drive with a dead speedometer?
For a short trip, carefully, yes – but you can't see your speed, shifting may be poor and ABS may be disabled. Use a phone GPS app for speed and get it repaired soon.
Why does my transmission stay in one gear?
Shift points are calculated from vehicle speed. Without a valid signal many transmissions switch to a fail-safe mode that holds one gear to protect themselves.
Can I just clean the sensor?
If the sensor is magnetic and covered with metal particles, cleaning often restores the signal. Find out where the particles come from, though – worn gears or bearings may need attention too.