What it means
The vehicle speed sensor (VSS) signal is missing or implausible. On automatic transmissions this often disables cruise control and shift adaptation; ABS-equipped cars typically derive speed from wheel speed sensors as a fallback.
At a glance
- Usually lights the check-engine light
How it works
Vehicle speed sensor A supplies the ECU with information about how fast the vehicle is moving. P0500 sets when the expected speed signal is missing or implausible, which can also affect systems that use vehicle speed for cruise control or transmission operation.
Common causes
Most likely first.
- Speed sensor failed
- Wiring or connector fault
Symptoms
- Check-engine light on
- Speedometer not working or reading erratically
- Cruise control unavailable
- Automatic transmission shifts feel abnormal
How to diagnose it
- Check freeze-frame data and live vehicle-speed readings while comparing the scan tool with the speedometer to establish whether the signal is absent or erratic.
- Inspect sensor A's connector and wiring for damage, loose contacts, corrosion, or chafing.
- Use vehicle service information to identify where speed sensor A gets its signal, then inspect the sensor and its target or reluctor for damage or contamination.
- Check the sensor's power, ground, and signal circuits as applicable against the manufacturer's wiring information.
- If the wiring and target are sound, test sensor A's output under the manufacturer's procedure before replacing it.
Common fixes
- Reconnect or clean poor contacts at the speed sensor A connector.
- Repair damaged sensor A wiring.
- Clean or repair a damaged sensor target or reluctor, where serviceable.
- Replace vehicle speed sensor A if its output fails testing.
Can I keep driving?
Drive cautiously only if the speedometer works reliably and shifting feels normal; avoid using cruise control. If the speed reading is missing or transmission shifts are abnormal, limit driving and arrange diagnosis because vehicle-speed-dependent functions may not work correctly.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.