P0502 — Vehicle Speed Sensor Low Input
Drive with caution — fix soon.
What P0502 means
This code means the engine computer is seeing a vehicle speed sensor signal that's too low, often near zero, while the car is actually moving. It usually points to a failed speed sensor, an open or shorted wire, or a poor ground connection. It's typically fixable by replacing the sensor or repairing the wiring, and it rarely involves major mechanical work.
Common symptoms
- Check engine light is on
- Speedometer reads low or stays at zero while driving
- Cruise control won't engage
- Harsh or delayed transmission shifting
- Possible speedometer dropouts at speed
Common causes
- Failed vehicle speed sensor
- Open or shorted wiring to the sensor
- Poor ground connection in the sensor circuit
- Corroded or loose connector
- Faulty transmission output speed sensor
Typical repair cost
$110 – $400
Varies by vehicle and root cause.
Frequently asked questions
Can I keep driving with a P0502 code?
Usually yes, but with caution. Your speedometer may read low or zero and cruise control likely won't work, which affects safety. Shifting can also feel rough. Drive carefully and have it checked soon.
How much does it cost to fix a P0502 code?
Most repairs cost $110 to $400. Replacing the speed sensor is the usual and most affordable fix, while wiring or ground repairs can add to the bill. A diagnosis confirms whether it's the sensor or the circuit.
Is a P0502 code serious?
It's moderately serious. The car still runs, but a low or missing speed signal affects the speedometer, cruise control, and shifting, all of which have safety implications. It's worth fixing soon.
Why does my speedometer read zero with a P0502 code?
A low-input code means the speed signal is too weak or near zero, often from a failed sensor or a broken wire. Since the speedometer relies on that signal, it can stay at zero even while you're driving until the sensor or wiring is repaired.