Damaged or corroded wiring harness at the left rear wheel speed sensor connector; Open circuit in the sensor pigtail or main harness between the sensor and ABS module; Failed left rear wheel speed sensor; Debris or metallic particles on the sensor tip or tone ring; Damaged tone ring (reluctor) on the left rear hub or axle; Water intrusion or corrosion inside the sensor connector; Faulty ABS control module (less common)

DTC codes / C06xx · Brakes, steering and suspension / C065F

C065FLeft Rear Wheel Speed Sensor B Circuit/Open

Q: What does code C065F mean?

Left Rear Wheel Speed Sensor B Circuit/Open. C065F indicates that the anti-lock brake system (ABS) control module has detected an open circuit or abnormal voltage on the left rear wheel speed sensor's 'B' signal circuit. The module monitors the sensor's output and flags this code when the signal is missing, intermittent, or outside the expected range, which prevents reliable wheel speed data for that corner.

C065F indicates that the anti-lock brake system (ABS) control module has detected an open circuit or abnormal voltage on the left rear wheel speed sensor's 'B' signal circuit. The module monitors the sensor's output and flags this code when the signal is missing, intermittent, or outside the expected range, which prevents reliable wheel speed data for that corner.

SystemChassis

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaBrakes, steering and suspension

Symptoms you may notice

ABS warning light illuminated on the dashboard
Traction control or stability control warning light also on
Often no symptoms besides the warning light
ABS may deactivate, leading to wheel lockup during hard braking
Traction control may not engage, causing wheel spin on slippery surfaces
Intermittent speedometer fluctuation if the sensor signal is erratic

Common causes, most likely first

Damaged or corroded wiring harness at the left rear wheel speed sensor connector
Open circuit in the sensor pigtail or main harness between the sensor and ABS module
Failed left rear wheel speed sensor
Debris or metallic particles on the sensor tip or tone ring
Damaged tone ring (reluctor) on the left rear hub or axle
Water intrusion or corrosion inside the sensor connector
Faulty ABS control module (less common)

How to diagnose and fix it

Inspect the left rear wheel speed sensor connector and wiring for corrosion, damage, or loose pins
Check the sensor's resistance and compare to the manufacturer's specification
Perform a visual inspection of the tone ring for cracks, missing teeth, or debris
Back-probe the sensor circuit at the ABS module and check for continuity and short to ground
Clear the code and test-drive while monitoring live wheel speed data to see if the signal drops out
Replace the left rear wheel speed sensor if resistance or signal is out of specification
Repair or replace damaged wiring harness sections and re-test the system

What the code does not always mean

A code for an open circuit does not automatically mean the sensor has failed; a corroded connector or chafed wire is a frequent culprit.
Metallic debris on the sensor tip can mimic an open circuit by disrupting the magnetic signal, so clean the sensor before condemning it.
The 'B' circuit designation may refer to a secondary signal line on some sensors, so consult the specific wiring diagram for your vehicle.
Intermittent faults often appear only when the suspension flexes or the wheel turns, so wiggle-test the harness while watching live data.
A failing tone ring can produce the same code as a bad sensor, and replacing the sensor alone will not fix the problem.

Can I keep driving with C065F?

You can usually drive the vehicle with this code, but the ABS and traction control systems may be disabled, increasing stopping distances on slippery surfaces. Avoid hard braking or aggressive driving until the fault is repaired.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.