C0040 on Ford
Right Front Wheel Speed Sensor Circuit
C0040 on Ford vehicles indicates right front wheel speed sensor circuit. Au7o has documented this code across 2 Ford models — most commonly on Focus, Transit Connect. This is a brake/ABS-system code. The right front wheel speed sensor measures how fast that wheel is rotating and feeds that data to the anti-lock brake, traction control, and stability control systems. C0040 means the ABS module found an electrical problem in the right front wheel speed sensor circuit — for example an open circuit, a short, or a signal that is missing or out of range. You'll normally see the ABS and traction/stability lights come on, and those systems may shut off temporarily while your regular brakes keep working. Typical repair costs on Ford range from $120 to $650, depending on the specific model and root cause.
Common Causes of C0040
- •Failed right front wheel speed sensor
- •Damaged, corroded or unplugged sensor wiring/connector
- •Damaged or rust-clogged tone/reluctor ring
- •Excessive air gap between sensor and tone ring
- •Wheel bearing wear affecting an integrated sensor
- •Water intrusion or corrosion at the connector
- •Faulty ABS control module (less common)
C0040 on Ford by Model
Ford Focus(1 issue)
- Rear Wheel Bearing Premature Failure (1st-Generation Mk1/Mk1.5)2000-2007
1999-2007 Ford Focus (1st-generation Mk1 and Mk1.5) suffer from repeated rear wheel bearing failures, often within months of replacement. One Focus Fanatics owner reported the left rear wheel bearing failing 4 times in 7 months. Root cause is missing or degraded inboard spindle seals that allow brake dust and water into the bearing race, plus alignment drift (excessive negative camber or toe) accelerating wear. Ford acknowledged the seal design in owner communities but never issued a formal recall. Replacement requires the full hub assembly. The 2012-2018 Mk3 Focus has separate bearing issues with different root causes (not covered by this entry).
Ford Transit Connect(1 issue)
- ABS Wheel Speed Sensor/Wiring Fault (ABS/Traction Control Lights On)2014-2021
Transit Connect owners report intermittent ABS and traction control warnings caused by wheel speed sensor signal dropouts, often due to sensor contamination, corrosion at connectors, or damaged wiring near the hubs. The issue can be intermittent and may also disable stability control functions until repaired. This pattern appears in NHTSA complaints and owner reports describing ABS/AdvanceTrac warnings and sensor replacement.
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What does C0040 mean on Ford?▼
C0040 stands for "Right Front Wheel Speed Sensor Circuit." This is a brake/ABS-system code. The right front wheel speed sensor measures how fast that wheel is rotating and feeds that data to the anti-lock brake, traction control, and stability control systems. C0040 means the ABS module found an electrical problem in the right front wheel speed sensor circuit — for example an open circuit, a short, or a signal that is missing or out of range. You'll normally see the ABS and traction/stability lights come on, and those systems may shut off temporarily while your regular brakes keep working. On Ford specifically, this code is documented across 2 models.
What causes C0040 on Ford vehicles?▼
Common causes on Ford: Failed right front wheel speed sensor, Damaged, corroded or unplugged sensor wiring/connector, Damaged or rust-clogged tone/reluctor ring, Excessive air gap between sensor and tone ring, Wheel bearing wear affecting an integrated sensor. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix C0040 on a Ford?▼
Repair costs on Ford range from $120 to $650, depending on the specific model and root cause.
Which Ford models have C0040 documented?▼
Au7o has documented C0040 on 2 Ford models: Focus, Transit Connect.