P0502 Code: Vehicle Speed Sensor A Circuit Low Input
🟠 Moderate severity · drivable
Drivable, but the speedometer may stop working and the transmission may shift hard; fix it soon.
What P0502 means
The vehicle speed sensor (VSS) signal is too low, which the computer reads as almost no speed signal. The VSS measures road speed so the computer can run the speedometer, cruise control, and transmission. A low input usually means the sensor is dead, its wiring is open or shorted, or the sensor is not picking up the rotating part it reads.
Symptoms
- Check engine light is on
- Speedometer not working
- Cruise control inoperative
- Harsh or erratic transmission shifts
Common causes
- most common: Faulty vehicle speed sensor
- common: Open or shorted sensor wiring
- common: Loose or corroded sensor connector
- less common: Damaged sensor ring or tone wheel
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Inspect and clean the sensor connector | Yes | $0–50 |
| Replace the vehicle speed sensor | Yes | $30–150 |
| Repair damaged speed sensor wiring | Mechanic | $50–200 |
Frequently asked questions
Can I drive with a P0502 code?
Yes, but without a working speedometer you cannot easily see how fast you are going. Get it repaired soon.
What does low input mean for a speed sensor?
It means the sensor is producing almost no voltage, usually because it failed or its wiring is damaged.
How much does it cost to fix a P0502?
A replacement speed sensor costs about $30–$150. Wiring repairs typically run $50–$200.
Related codes
P0500
P0500 Code: Vehicle Speed Sensor (VSS) Malfunction
P0501P0501 Code: Vehicle Speed Sensor A Circuit Range/Performance
P0503P0503 Code: Vehicle Speed Sensor A Circuit Intermittent/Erratic/High
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.