Data Erratic, Road Speed Information
The ECU is receiving erratic road speed data.
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 computer thinks the speed you’re going is bouncing around too much to be real, making it confused about how fast you're driving.
What the computer is actually seeing
The engine control unit (ECU) gauges road speed based on input from sensors; erratic readings (over 10 mph variations within a second) signal a problem.
What a healthy reading looks like
Road speed should reliably range from 0 to vehicle max speed; erratic readings exceed > 10 mph; normal input signals should be stable within +/- 1 mph.
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 for any visible wiring damage or loose connections around the vehicle speed sensor (VSS).
- 2Test the vehicle speed sensor output with a multimeter; expect a variable voltage output between 0-5V based on speed.
- 3Inspect the ECU grounds. Ensure they are clean and tightly connected; check for any corrosion or rust.
- 4If VSS checks out, monitor for other fault codes that may include wheel speed sensors or output signal issues.
- 5Replace the VSS if the output is not within expected values; if it checks out, suspect ECU related problems.
Common causes
- Faulty vehicle speed sensor (VSS)
- Wiring issues like shorts or open circuits
- Faulty ECU
- Poor ground connection
- Wheel speed sensor issues
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
You can drive, but expect possible erratic speed readings which can impact transmission performance.
Will this code come back after repairs?
If the underlying issue is truly fixed, it shouldn't return.
Why do I get this code with SPN 101?
Both codes relate to vehicle speed; one measures sensor output, the other measures ECU processing.
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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