C0040: How to Diagnose & Fix — Right Front Wheel Speed Sensor Circuit
22 vehicles · 9 makes · $90-$1,200 repair
How to diagnose and fix C0040: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Chrysler 300 · 2011–2023
ABS control module suffers internal failures due to short circuits in main circuit board. Prevents proper ABS operation and stores fault codes. While regular braking functions, vehicle loses anti-lock capability, traction control, and stability control.
Common Symptoms
- ABS warning light constantly illuminated
- BAS warning light
- Traction control warning
- U0121 code (lost communication with ABS)
- No ABS function during hard braking
How to Fix
ABS module replacement or professional rebuild service. Check all wheel speed sensors and wiring before replacement. Many specialty shops offer rebuild for $300-500 with warranty. OEM module requires programming to VIN.
Sources for this issue (1)
Chevrolet Avalanche · 2002–2006
First-generation Avalanches (2002-2006) can experience unwanted ABS activation during normal low-speed braking. The antilock brake system activates inappropriately, causing a pulsating brake pedal and increased stopping distances when it should not be engaging. The issue is more likely in environmentally corrosive areas where corrosion builds up between the front wheel speed sensor and the hub/bearing assembly it mounts to, weakening the sensor signal. This creates a safety hazard as the vehicle takes longer to stop than expected during routine braking.
Common Symptoms
- ABS activates during normal low-speed braking
- Pulsating brake pedal when it should not be pulsating
- Increased stopping distances during routine stops
- ABS warning light illuminated on dashboard
- Grinding or buzzing noise from brakes during normal stops
How to Fix
Inspect and clean all four ABS wheel speed sensors and tone rings. Replace corroded sensor wiring or connectors. If the ABS module itself is faulty, replacement costs $600-$1,200. Applying dielectric grease to sensor connectors during brake service can prevent corrosion. In some cases, ABS module reprogramming at the dealer resolves the issue.
Sources for this issue (2)
Jeep Grand Wagoneer · 2022–2024
NHTSA complaints and owner reports describe intermittent ABS/ESC warnings on Grand Wagoneer tied to wheel speed sensor signal loss or erratic readings, sometimes after wet weather or road debris impacts. When the system detects implausible wheel speed data, it can disable ABS/ESC functions and illuminate multiple warnings.
Common Symptoms
- ABS light on
- ESC/traction control light on
- Cruise control disabled
- Brake pedal pulsation changes or ABS inoperative message
- Intermittent warnings that reset after key cycle
How to Fix
Scan for ABS module faults, inspect wheel speed sensors and wiring at each hub, and check tone rings/encoder surfaces for damage or contamination. Replace the affected wheel speed sensor/hub assembly as needed and clear codes; verify with a road test and live wheel-speed data.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Mopar 68609615AA front-left wheel-speed sensor with auto levelOEMMopar 68609615AA
Front-left sensor replacement after live data and circuit inspection isolate that corner on an auto-level vehicle Fitment/availability: 2022-2025 Grand Wagoneer, driver-side front, with auto level. Not the passenger side, rear axle or wi…
- Genuine Mopar 68609616AA front-right wheel-speed sensor with auto levelOEMMopar 68609616AA
Front-right sensor replacement after live data and circuit inspection isolate that corner on an auto-level vehicle Fitment/availability: 2022-2024 Grand Wagoneer, passenger-side front, with auto level. Not the driver side, rear axle or w…
- Genuine Mopar 68424418AD front wheel-speed sensor without auto levelOEMMopar 68424418AD
Front sensor replacement after diagnosis on a vehicle confirmed not to have auto level Fitment/availability: 2022 Grand Wagoneer front left or right without auto level according to the exact catalog. Confirm VIN and later-year supersessi…
- Genuine Mopar 68422140AA front hub-and-bearing assemblyOEMMopar 68422140AA
Confirm VIN/current supersession and do not use for an isolated sensor/wiring fault or rear axle.
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Sources for this issue (1)
Ford Transit Connect · 2014–2021
Jeep Patriot · 2007–2017
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C0040 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does C0040 mean?
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.
What are the most common causes of C0040?
The most common causes of C0040 are: 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). The specific cause varies by vehicle.
How much does it cost to fix C0040?
Repair costs for C0040 range from $90 to $1,200, depending on the vehicle and root cause.
Which vehicles are affected by C0040?
Au7o has documented C0040 across 22 vehicle models from 9 manufacturers: Chevrolet, Chrysler, Ford, GMC, Honda, Jeep, Lincoln, Pontiac, RAM.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.