Vehicle Speed Sensor A
Indicates an issue with the 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 tracks how fast the vehicle is moving and sends that data to the engine control module (ECM). If it malfunctions, the speed reading can be incorrect, affecting transmission shifts and vehicle performance.
What the computer is actually seeing
The ECM expects the vehicle speed signal to be within a certain range (0-500 Hz) corresponding to vehicle movement. If the sensor fails, it may show a constant low voltage signal (around 0V) or a drop in frequency at higher speeds.
What a healthy reading looks like
Speed readings should correlate with vehicle speed: 0 mph = 0 Hz, 15 mph = 3 Hz, 30 mph = 6 Hz, etc.
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.
- 11. Inspect the vehicle speed sensor wiring and connectors for damage or corrosion. If faulty, repair or replace the wiring/connectors. Decide: Is the wiring okay? If NO, fix it first.
- 22. Check the output voltage of the vehicle speed sensor while the vehicle is in motion. Expected voltage should range from 0.5V-5V. If abnormal, decide: Is the voltage reading correct? If NO, replace the speed sensor.
- 33. Verify the ECM is properly configured and doesn't have a software issue by checking for updates or consulting service manuals. Decide: Is the ECM functioning properly? If NO, consider reprogramming or replacing the ECM.
Common causes
- Faulty vehicle speed sensor
- Damaged wiring or connectors
- ECM software issue
- Transmission problems
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code active?
It's not immediately dangerous, but you'll likely experience erratic shifting and speedometer failure, so fix it soon.
Will this code come back after clearing?
Yes, if the underlying issue isn't repaired, the code will likely reappear.
Why does this code sometimes pair with transmission issues?
The vehicle speed sensor directly affects transmission performance, so if it's faulty, it can cause shifting problems.
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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