Rear Wheel Speed Sensor Circuit
The rear wheel speed sensor has a malfunction.
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 rear wheel speed sensor measures how fast the wheel is turning. If the computer sees a problem with the sensor, it can trigger this code.
What the computer is actually seeing
The ABS control module receives inputs from the rear wheel speed sensor. If it detects a speed reading that’s significantly lower than expected—like less than 0.5 volts at speed—it throws the C0844 code.
What a healthy reading looks like
Expected voltage from the rear wheel speed sensor is typically around 0.5V to 2.5V when stationary. During movement, it should fluctuate based on wheel rotation, often reaching around 5V during a healthy operation.
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 connectors for the rear wheel speed sensor. Look for frayed wires or corrosion. Is there physical damage?
- 22. Use a multimeter to measure the voltage at the rear wheel speed sensor connector. Is the voltage fluctuating between 0.5V to 2.5V when the vehicle is stationary?
- 33. If the sensor voltage is incorrect, swap the rear wheel speed sensor with a known good unit. Does the code reset and does the voltage return to expected values?
- 44. If the sensor tests good, inspect the ABS control module. Are there other fault codes present? If so, those may need to be addressed before this code clears.
Common causes
- Faulty rear wheel speed sensor
- Wiring issues (damaged or corroded connectors)
- Improperly installed or damaged sensor mount
- Faulty ABS control module
Typical repair cost
$$-$$$
Related codes
Frequently asked questions
Is it safe to drive with code C0844?
It's generally drivable, but be aware of potential issues with ABS and stability control.
Will this code come back after clearing?
If the underlying issue isn't fixed, the code will likely return.
Why do I see code C0844 alongside C0854?
Both codes relate to wheel speed sensor issues; typically they can occur together if there are sensor or wiring faults.
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