Vehicle Speed Sensor A - Fault
Indicates a problem with the primary vehicle speed sensor.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The vehicle speed sensor monitors how fast the vehicle is moving and sends that info to the computer; if it fails, the computer can't accurately tell how fast you're going.
What the computer is actually seeing
The ECM (Engine Control Module) expects a voltage signal that varies with speed, typically between 0.5V and 2.5V at idle and up to 5V at speed. If it sees a constant voltage or no voltage change, it triggers the fault code.
What a healthy reading looks like
0.5V at idle to 5V while driving; speed signal should change as vehicle speed changes.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 1Check wiring and connector to the vehicle speed sensor for damage or corrosion. If damaged, repair or replace as necessary.
- 2Monitor the voltage signal from the vehicle speed sensor using a multimeter while the vehicle is in motion. Expect values between 0.5V (idle) and 5V (driving). If voltages are out of range, proceed.
- 3If the sensor's voltage signal is normal but the code persists, check for any ECM software updates or consider testing the ECM itself.
Common causes
- Faulty vehicle speed sensor
- Wiring issues or damaged connectors
- ECM software issues or failures
Typical repair cost
$$ ($100 - $400)
Related codes
Frequently asked questions
Is it safe to drive with this code?
Driving is possible, but you may experience inaccurate speed readings and cruise control issues. Fix soon.
Will this code come back after clearing?
Yes, if the underlying issue isn't resolved, it will likely return.
Why does this code sometimes come with other speed-related codes?
Multiple speed sensor codes can indicate a common issue affecting the vehicle's speed signal or several components related to speed measurement.
Working a real vehicle right now?
Let DiagCoach walk you through it live with your specific symptoms, vehicle, and what you've already checked.
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