C003B — Right Rear Wheel Speed Sensor Supply (Subfault)

C003B — C003B — Right Rear Wheel Speed Sensor Supply (Subfault): Causes, Symptoms & Fix. A fault in the ABS / stability control. Short, gentle driving to a shop is usually possible. Typical causes: damaged tone (reluctor) ring on the hub, failed wheel speed sensor, faulty ABS module or pump motor.

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Is it safe to drive?

Drive with caution The base brakes usually still work, so careful driving is possible — but ABS and stability control are disabled, which lengthens stopping distances on slippery roads. Fix promptly and avoid harsh driving.

How to diagnose with an OBD scanner

Read the code and freeze frame Connect an OBD2 scanner, confirm C003B is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many C0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the ABS / stability control for damage, corrosion, chafing or poor contact.
Subsystem check Read all four wheel speed PIDs while driving slowly — the faulty sensor drops out or reads implausibly.
Subsystem check Inspect the sensor and tone ring for metal debris and damage near the hub.
Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm C003B does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for C003B (parts and labor, USD, independent shop rates): Replace a wheel speed sensor: $120–$350; ABS module repair or replacement: $400–$1,200; Repair sensor wiring: $80–$250. Overall, fixing C003B usually costs between $80 and $1,200. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

How do I diagnose C003B myself?

Start with a scan: confirm C003B, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the ABS / stability control, and verify the suspect component against live data before buying parts.

Is it safe to drive with C003B?

The base brakes usually still work, so careful driving is possible — but ABS and stability control are disabled, which lengthens stopping distances on slippery roads. Fix promptly and avoid harsh driving.

Will C003B clear itself?

Sometimes C003B clears after a few drive cycles if the fault was intermittent — for example a loose connector or a tank of bad fuel. The underlying cause usually remains, so the code tends to return. Clear it once; if it comes back, diagnose rather than erase it repeatedly.

What are the symptoms of C003B?

Drivers most often notice: speedometer or cruise control issues, stability control disabled message, brake pedal pulsation changes, ABS or ESC warning light on.

How much does it cost to fix C003B?

Replace a wheel speed sensor — $120–$350; ABS module repair or replacement — $400–$1,200; Repair sensor wiring — $80–$250. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

C003B — C003B — Right Rear Wheel Speed Sensor Supply (Subfault): Causes, Symptoms & Fix

When your vehicle's anti-lock braking system detects a problem with the power source feeding the right rear wheel speed sensor, it logs trouble code C003B. This fault points to an electrical supply issue rather than a problem with the sensor itself or the reluctor ring. The ABS control module relies on stable voltage to poll all four wheel speed sensors continuously, and when that supply to the right rear corner falters, the module flags C003B and illuminates the dashboard warning light.

Modern ABS and electronic stability control systems depend on each wheel speed sensor providing real-time rotational data. These sensors work alongside a tone ring (reluctor) mounted to the hub or CV axle to generate a pulsed signal proportional to wheel speed. The module supplies a reference voltage to each sensor circuit and monitors the returning signal. If the supply voltage collapses, the sensor goes dark, and the module can no longer track that wheel's speed. Under these conditions, the stability system disables itself because it cannot safely interpret vehicle dynamics without complete four-wheel data. C003B specifically flags the supply rail feeding the right rear sensor as the culprit, though the underlying cause could be upstream—a blown fuse, wiring damage, or a failing module output stage.

After C003B sets, the module saves freeze frame data capturing engine RPM, vehicle load, coolant temperature, and road speed at the exact moment of failure. That snapshot is the most valuable starting point for diagnosis, because it tells you what conditions triggered the fault and guides your road test verification later.

Symptoms

The ABS warning lamp stays lit on the instrument cluster
Electronic stability control (ESC) stops functioning, often triggering a dedicated "disabled" message
The speedometer may display incorrect vehicle speed or become erratic
Cruise control can disengage or refuse to activate
Braking feel changes noticeably—pedal pulsation may disappear or feel different during hard stops
On slippery surfaces, the vehicle may skid or pull more than normal during braking
In some cases, no obvious drivability symptoms occur beyond the warning light

Causes

Blown fuse supplying voltage to the ABS module's sensor reference circuit (most common and cheapest to fix)
Damaged or corroded wiring harness near the right rear wheel well, often from road debris or moisture intrusion
Poor electrical connection at the wheel speed sensor connector, including bent pins or moisture-induced corrosion
Failed wheel speed sensor internal to the right rear assembly
Tone ring (reluctor) coated with metallic debris or physically damaged, causing intermittent signal dropout
Internal fault within the ABS control module affecting its sensor power supply output stage
Short-to-ground or open circuit in the sensor wiring from accident damage or prior repairs

How to Diagnose C003B

Connect a quality OBD2 scanner, retrieve code C003B, and record all freeze frame data—this tells you engine load, RPM, temperature, and speed when the failure occurred.
Scan every module on the CAN bus for additional trouble codes. Related P0300-type misfire codes or chassis CAN faults often point to the true root cause, and manufacturer TSBs database (searchable by VIN at the OEM site or nhtsa.gov) may reveal a known fix for your specific make and model.
Perform a visual inspection of the right rear wheel well wiring harness, paying close attention to the connector body, terminal pins, and any chafed or cracked insulation near the suspension movement points.
Back-probe the sensor connector with a multimeter while an assistant rotates the wheel—check for clean square-wave signal output and verify reference voltage is present at the supply pin.
Inspect the tone ring through the wheel hub for metal contamination, chips, or misalignment that could create signal gaps even if the sensor and wiring check out.
Clear the code, replicate the freeze frame conditions on a test drive, and verify C003B does not return before considering the repair complete.

Repair Options and Costs

Replace the right rear wheel speed sensor: $120–$350 (parts range $40–$120; labor typically 0.5–1.0 hour at shop rates)
Repair damaged sensor wiring or connector: $80–$250 depending on harness section needing repair or replacement
Replace or remanufacture the ABS hydraulic control module: $400–$1,200 (new or reman unit plus programming)

Total Repair Cost

Overall, fixing C003B typically runs between $80 and $1,200 depending on which component is actually at fault. The most common and least expensive fix is a blown fuse or simple wiring repair. Wheel speed sensor replacement falls in the mid-range, while ABS module replacement or repair represents the high-end scenario. Always confirm the root cause through proper diagnosis before purchasing parts—spending $800 on a new module when the issue is a $5 fuse wastes money and delays the actual repair.

Can You Drive with C003B?

Standard friction brakes remain fully functional, so you can drive the vehicle cautiously. However, ABS and stability control are disabled, meaning your stopping distance increases on wet, icy, or loose surfaces and you lose the ability to modulate brake pressure automatically during emergency maneuvers. Treat this code as a caution-level issue: get it diagnosed promptly and avoid aggressive driving until repaired.