C0039 — Right Rear Tone Wheel (Subfault) #

Note: The wording of this DTC (Diagnostic Trouble Code) may vary depending on the vehicle manufacturer.

• Right Rear Wheel Speed Sensor Tone Wheel Fault (Ford, GM)
• Right Rear ABS Sensor Ring Malfunction (Toyota, Honda)
• Right Rear Wheel Pulse Ring Error (BMW, Mercedes-Benz)

Summary for code C0039 #

The C0039 code is an OBD-II chassis code associated with the right rear tone wheel, a slotted or toothed ring that works with the wheel speed sensor for the Anti-lock Braking System (ABS). When the Engine Control Module (ECM) or ABS module detects abnormal signals or a loss of signal from this tone wheel, it triggers this code. Usually, this points to issues with the physical tone wheel, the sensor, or related wiring. Left unresolved, it can impact ABS function and, in some cases, traction or stability control. Addressing this code quickly is important for maintaining safe braking performance.

Common symptoms for code C0039 #

A C0039 code often reveals itself through changes in vehicle behavior, especially under braking. While some symptoms can be subtle, others are hard to miss. Watch out for:

• ABS warning light illuminated on the dashboard
• Traction control or stability control light on
• Pulsation or unusual noise during braking
• Loss of ABS function (wheels may lock under hard braking)
• Intermittent or complete loss of traction/stability assist

Probable causes for code C0039 #

C0039 is most often the result of physical or electrical issues related to the right rear wheel speed sensing system. The most frequent root causes, ranked in order of occurrence, are:

1. Damaged or dirty right rear tone wheel (corrosion, cracks, missing teeth, or debris)
2. Faulty right rear wheel speed sensor
3. Broken, corroded, or loose wiring/connectors at the sensor or ABS module
4. Improperly installed wheel bearing or hub assembly (affecting tone wheel alignment)
5. Malfunctioning ABS control module (less common)

Step-by-step diagnosis for code C0039 #

Proper diagnosis is key to saving time and money. Follow these steps to pinpoint the issue:

• 1. Confirm the code with a professional scan tool; note any related codes (especially wheel speed sensor or ABS codes).
• 2. Perform a visual inspection of the right rear tone wheel, sensor, and wiring for visible damage, debris, or corrosion.
• 3. Clean the tone wheel and sensor (even small debris can cause signal issues).
• 4. Test the right rear wheel speed sensor with a multimeter or scan tool for signal output and continuity.
• 5. Inspect connectors for loose pins or corrosion; repair as needed.
• 6. Check wheel bearing/hub alignment to ensure the tone wheel is correctly positioned relative to the sensor.
• 7. If all else fails, test the ABS control module as a last step, as module failure is rare but possible.

Possible repairs for code C0039 #

Fixes for C0039 are closely tied to the underlying cause. After diagnosis, consider these repair options:

• Clean the right rear tone wheel and sensor area to remove dirt or debris.
• Replace the right rear tone wheel if it is cracked, corroded, or missing teeth.
• Replace or repair the right rear wheel speed sensor if faulty.
• Repair or replace damaged wiring or connectors between the sensor and ABS control module.
• Reinstall or replace wheel bearing/hub assembly if poor alignment is detected.
• Replace the ABS control module only if all other faults are ruled out.

Is it safe to drive with code C0039? #

Driving with code C0039 is not recommended for extended periods. While the vehicle may operate normally under gentle driving, the loss of ABS and possibly traction or stability control can increase stopping distances and reduce control during emergency maneuvers or slippery conditions. If the ABS warning light is on, proceed cautiously and schedule repairs as soon as possible.

Vehicles most commonly affected by code C0039 #

This code is most frequently reported on models with ABS and advanced electronic stability systems, especially:

• Chevrolet Silverado, Tahoe, Suburban
• Ford F-150, Explorer, Edge
• Honda Accord, CR-V
• Toyota Camry, RAV4, Tacoma
• BMW 3 Series, X5
• Mercedes-Benz C-Class, E-Class

Common mistakes & best practices for code C0039 #

Misdiagnosis or rushed repairs can lead to frustration and wasted money. Here are classic pitfalls and tips:

• Only replacing the sensor without inspecting the tone wheel for damage or debris
• Overlooking wiring/connectors—corrosion or loose pins are frequent culprits
• Not resetting the code after repair, which may leave warning lights on
• Skipping a road test to confirm the fix and proper ABS operation
• Rushing to replace the ABS module before thoroughly checking mechanical and wiring issues

Express FAQ for code C0039 #

Here are quick answers to common questions about this code:

• Q: Can a bad tone wheel cause other ABS codes?
  A: Absolutely. A damaged tone wheel can trigger multiple wheel speed sensor codes or generic ABS faults.
• Q: Do I need special tools to fix C0039?
  A: Basic hand tools and a scan tool or code reader are usually sufficient. A multimeter can help test wiring and sensors.
• Q: Will C0039 reset itself if I clean the tone wheel?
  A: Sometimes. If the root cause is resolved, the code may clear after a few drive cycles, but it’s best to clear it manually with a scan tool.