Rear Wheel Speed Sensor A Circuit Open
The computer detected an open circuit in the rear wheel speed sensor A.
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What it means (plain English)
Your vehicle's computer looks for signals from the rear wheel speed sensor to know how fast the wheel is turning. If it gets no signal at all, it flags this code.
What the computer is actually seeing
The ABS or stability control module expects a voltage signal from the rear wheel speed sensor in the range of 0.5-12 volts. If it does not see any voltage (open circuit) for more than a specified time (usually several milliseconds), it triggers this fault code.
What a healthy reading looks like
Look for a voltage signal from the sensor between 0.5V to 12V while the wheel is turning; otherwise, it indicates an open circuit.
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 wiring and connector at the rear wheel speed sensor for damage or corrosion. Repair as needed. Decision: Does the wiring look intact? Yes: Go to step 2. No: Repair wiring and retest.
- 22. Measure the voltage at the sensor connector with the ignition on (engine off). Expect a voltage reading. Decision: Do you see 0.5V or higher? Yes: Go to step 3. No: Check for an open circuit back to the module, and repair if necessary.
- 33. Test the rear wheel speed sensor by disconnecting it and checking resistance across its terminals. Expect a resistance between 800-1200 ohms. Decision: Is the resistance within specs? Yes: Replace the rear wheel speed sensor. No: Repair wiring or replace damaged components.
Common causes
- Damaged wiring harness to the rear wheel speed sensor
- Corroded or faulty connector pins
- Failed rear wheel speed sensor
- Faulty ABS or stability control module
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It’s safer to not drive the vehicle until you address this code, as it can affect braking and traction control.
Will this code come back after I clear it?
It can return if the underlying issue is not fixed. Always address the root cause.
Why might this code appear alongside another code?
Codes can appear together if they relate to similar system functions, like multiple sensors or wiring issues affecting the same system.
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