Vehicle Speed Signal Missing or Invalid
The system detects an issue with the vehicle speed signal.
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's computer isn't receiving a reliable speed signal from the speed sensor, which usually happens because of a faulty sensor or wiring issues.
What the computer is actually seeing
The engine control module (ECM) expects a varying voltage signal from the vehicle speed sensor, typically between 0.5 to 4.5 volts as the vehicle speeds up, but instead sees a flat or missing signal after a certain point.
What a healthy reading looks like
Voltage should range between 0.5V (no movement) and 4.5V (maximum speed). A steady 0V or no signal indicates a problem.
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 the vehicle's speed sensor wiring for any visible damage or corrosion. Repair as necessary. Decision: If wiring is good, proceed to next step.
- 2Use a multimeter to measure the voltage at the vehicle speed sensor connector with the vehicle in motion. Expected range is 0.5V to 4.5V. Decision: If no signal, replace the speed sensor. If signal present, check the ECM.
- 3Inspect the ECM's connections for any moisture or corrosion. Repair any issues found. Decision: If connections are fine, consider a software update or replacement of the ECM.
Common causes
- Faulty vehicle speed sensor
- Wiring issues or damaged connectors
- ECM software issue
- Faulty ABS module (in some vehicles)
- Wheel speed sensor misalignment or failure
Typical repair cost
$$$
Related codes
Frequently asked questions
Can I still drive my vehicle with this code?
Yes, but it may affect speedometer accuracy and cruise control functionality.
Will this error code disappear on its own?
It's unlikely. If the underlying issue isn't fixed, the code will likely reappear.
Why does this code pair with B1680?
Both codes are related to vehicle speed sensor performance issues.
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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