C003A Right rear wheel speed sensor circuit fault

ABS code C003A, right rear wheel speed sensor

C003A in short

C003A means the computer sees a fault in the right rear wheel speed sensor signal. The cause is often the sensor, its wiring or connector, or on some Ram trucks software. ABS and stability control switch off, so book a check soon; ordinary braking normally still works.

Each wheel has a speed sensor that reads a toothed or magnetic ring and tells the brake control module how fast that wheel turns. C003A is stored when the right rear signal is missing, out of range, erratic or does not match the other wheels.

Ram bulletins use extensions on the code: 2F means the signal is erratic, 62 means the signal does not compare with the other sensors, and 1D means circuit current out of range. Jeep's bulletin describes the same pair for the Wrangler.

With either rear sensor faulted, the module turns ABS, traction and stability control off and lights the ABS lamp. Owner reports also link it to cruise control not working, odd shifting and a limited top speed.

Most likely causes

  1. Rear wheel speed sensor, connector or wiring

    Supported by vehicle data
    Why it ranks here
    Owners of a Sprinter, Tiffin Wayfarer and Honda Accord report the dealer replacing or suspecting the sensor or hub, and Ram's Max Tow bulletin replaces both rear sensors; Jeep's Compass bulletin replaces all four for water in the sensor.
    What would change this
    Rises if live data shows one rear wheel dropping out or erratic while driving. Falls if all four wheel speeds track together.

  2. Brake control module software (Ram 3500)

    Supported by vehicle data
    Why it ranks here
    Ram bulletin 08-056-26 reprograms the brake system control module for these codes, with no sensor replacement.
    What would change this
    Rises if a dealer finds an open software update for your VIN. Falls if the module is already current.
    How to test the brake system control module (abs module)

  3. Axle vibration from rumble strips (Ram 3500 dually)

    Possible — needs testing
    Why it ranks here
    Ram's service note says the codes can set after highway rumble strips with no hardware fault found and that no repair exists yet.
    What would change this
    Rises if the code set right after rumble strips and clears. Falls if it sets on smooth road.

  4. Loose engine or chassis harness connector

    Possible — needs testing
    Why it ranks here
    One Dodge Charger had C0037-62 and C003A-62 set together with a loose engine harness connector, fixed by reseating it.
    What would change this
    Rises if both rear codes set together with other module codes. Falls if only one wheel is affected.

What to test first

Start at step 1. Each result tells you what it means and where to go next.

  1. Read all stored ABS codes with extension digits and note whether both rear sensors are listed.

    Low riskTool: scan tool that reads ABS codes

    • IfBoth C0037 and C003A are stored together

      It meansLook for a shared cause such as software or a harness connector.

      Go to step 2

    • IfOnly one rear wheel code is stored

      It meansThe sensor or its wiring on that wheel is the likelier cause.

      Go to step 3

  2. Ask a dealer whether your VIN has a brake module update or a sensor bulletin for these codes.

    Low risk

  3. With the scan tool, watch the four wheel speeds on a drive and note whether one rear speed drops out or is erratic.

    Best left to a shopTool: scan tool with live data

    Warning:Road testing with faulty ABS and stability control needs a careful driver; have a shop do it.

Symptoms

  • ABS and traction or stability control lights on
  • Cruise control or four-wheel drive unavailable
  • Speed limited, odd shifting or engine revving high
  • Red brake warning light on or the pedal feels different Gets more serious: stop and have it checked.

How to fix

This is a safety-critical system, so we explain the code but don't give repair steps. Have it inspected by a qualified technician.

Parts and cost context

  • Brake system control module (ABS module):Some Ram trucks need a software update rather than parts. Labour varies; get a quote.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Ram

  • 2020–2026 · 3500

    Supported by vehicle data

    Ram bulletins for the 3500 cover signal erratic and signal compare codes on both rear sensors: a module reprogram, replacing both rear sensors on Max Tow, and a hold on repairs when it follows rumble strips. An owner reports C0037-2F while towing a heavy trailer. Whether the bulletins are still current is not verified.

  • 08-056-26Status unverified

    Brake system control module update for C0037/C003A

    20263500 · issued · NHTSA 11028866

    Reprogram the brake system control module when C0037-2F or C003A-2F set the ABS light and disable ABS, trailer sway control and stability control.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 08-374-25Status unverified

    Max Tow rear wheel speed sensors, C0037/C003A

    20243500 · issued · NHTSA 11025631

    Replace both rear wheel speed sensors on Max Tow trucks that set signal compare or erratic faults for either rear sensor.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 9004400Status unverified

    Rear axle, wheel speed codes after rumble strips

    20223500 · issued · NHTSA 10218446

    On dual-rear-wheel high output trucks with these codes and no hardware fault, do not replace parts; clear codes and avoid rumble strips until a repair is released.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 05-004-24Status unverified

    Brake warning lamp over rumble strips

    20203500 · issued · NHTSA 11011716

    Brake warning lamp or MIL with rear wheel speed sensor codes after driving over rumble strips. The NHTSA summary was read for the code list only.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Jeep

  • 2020 · Wrangler

    Supported by vehicle data

    FCA bulletin 9004311 says to call before replacing a rear wheel speed sensor for these codes. Whether it is still current is not verified.

  • 2020 · Compass

    Supported by vehicle data

    A Compass bulletin replaces all four wheel speed sensors for oxidation or water intrusion that sets wheel speed codes.

  • 9004311Status unverified

    Rear wheel speed sensor C0037/C003A: call before replacing

    2020wrangler · issued · NHTSA 10183000

    Contact FCA technical support before replacing a rear wheel speed sensor for these codes.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 05-001-20Status unverified

    Replace four wheel speed sensors, oxidation or water

    2020compass · issued · NHTSA 10183067

    Replace all four wheel speed sensors when oxidation or water intrusion sets wheel speed codes.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Mercedes-Benz

  • 2012–2016 · Sprinter

    Supported by vehicle data

    Sprinter owners report C0037 or C003A with ABS, traction and engine lights; a dealer replaced a rear sensor, and one owner mentions an earlier rear sensor recall. Based on owner complaints.

Honda

  • 2018 · Accord

    Possible — needs testing

    An Accord owner reports C003A-62, right rear wheel speed sensor circuit short to ground or open, with the mechanic suspecting the wheel hub. Based on one complaint.

  • C0037Left rear wheel speed sensor circuit fault

    Same system Supported by vehicle data

    C0037 is the left rear wheel speed sensor; Ram and Jeep bulletins list both together.

All ABS, traction and stability control codes

C003A questions

Is it safe to drive with C003A?

Ordinary brakes usually still work, but ABS and stability control are off. Have it checked soon and stop if the red brake light comes on.

Should I replace the sensor first?

Check for bulletins first: some Ram trucks need a module update, and a Ram note says not to replace parts when the code follows rumble strips.

Sources and review

  1. Ram 08-056-26: Flash: Brake System Control Module (BSCM) Updates Updates Customers must experience a Malf — NHTSA manufacturer communications (flat file, NHTSA ID 11028866)
  2. Ram 08-374-25: Max Tow Right and Left Rear Wheel Speed Sensors Inoperable Customers must experience a Mal — NHTSA manufacturer communications (flat file, NHTSA ID 11025631)
  3. NHTSA complaint ODI 11749466: 2024 Ram 3500, C0037-2F — NHTSA Office of Defects Investigation
  4. NHTSA complaint ODI 11124129: 2016 Mercedes-Benz Sprinter 3500, C0037 then C003A — NHTSA Office of Defects Investigation
  5. NHTSA complaint ODI 11746593: 2018 Honda Accord, C003A-62 — NHTSA Office of Defects Investigation
  6. Jeep 05-001-20: Replacement of Front and Rear Wheel Speed Sensors Due to Oxidation or Water Intrusion Sett — NHTSA manufacturer communications (flat file, NHTSA ID 10183067)
  7. Ram 9004400: AXLE ASSEMBLY, Rear Complete On dual rear wheel high output trucks displaying wheel speed — NHTSA manufacturer communications (flat file, NHTSA ID 10218446)
  8. NHTSA complaint ODI 10464547: 2012 Dodge Charger, C0037-62 and C003A-62 — NHTSA Office of Defects Investigation
  9. Jeep 9004311: SENSOR, Wheel Speed Please call FCA Redacted Content prior to replacing a rear wheel spee — NHTSA manufacturer communications (flat file, NHTSA ID 10183000)
  10. NHTSA complaint ODI 11760939: 2012 Mercedes-Benz Sprinter 3500, C003A after recall — NHTSA Office of Defects Investigation
  11. NHTSA complaint ODI 11491472: 2012 Freightliner Sprinter 3500, C0037 and C003A — NHTSA Office of Defects Investigation
Last reviewed
Written by
Saurabh K.
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