Comprehensive diagnostic guide for OBD-II code C0117 Chassis / ABS-related

What This Code Means

• What C0117 is generally considered: C codes are chassis-related diagnostic trouble codes within the OBD-II framework, commonly tied to ABS, vehicle stability, and related wheel-speed sensing circuits. The exact meaning of C0117 is OEM-specific, and different manufacturers may define the fault slightly differently.
• On many vehicles, C0117 is associated with a wheel speed sensor input circuit fault (often involving the wheel speed sensor itself, wiring/connector, or ABS signal conditioning). Some OEMs attribute C0117 to left-front wheel speed sensor input issues or to a general wheel-speed signal fault in the ABS/ESP subsystem. Always verify the exact definition in the manufacturer service information for the vehicle you're diagnosing.
• For standard code structure reference: OBD-II codes are four-character alphanumeric values with a letter identifying the system (P = Powertrain, B = Body, C = Chassis, U = Network). C0117 falls under the chassis category.

Symptoms

• ABS light and/or Traction Control/Stability Light ON
• Intermittent or permanent loss of wheel-speed data in one or more wheels
• Erratic or blown speedometer behavior (in some vehicles, ABS wheel-speed data feeds speedometer or stability control)
• Unusual brake feel under light or moderate braking, especially at vehicle speeds where ABS should engage
• Cruise control may exhibit degraded performance or warning behavior if wheel-speed data is inconsistent
• In some cases, no other DTCs are present beyond C0117, or C0117 is accompanied by other ABS-related codes

Important safety and general considerations

• ABS/ESP systems use wheel-speed sensor signals to monitor each wheel's rotation. A faulty wheel-speed signal can affect braking performance and stability control. Do not drive aggressively with an active ABS/ESC fault; address the fault to restore proper braking dynamics.
• When diagnosing, consider vehicle battery condition and grounding, since poor voltage or grounding can corrupt sensor signals.
• Some tests involve wheel rotation with the vehicle supported or on a test surface; follow safe procedures, use wheel chocks, and avoid high-speed road tests while a fault is unresolved.

What to collect and inspect (data and visuals)

• Scan data and freeze-frame: Retrieve the DTCs (C0117) and any related ABS/ESP codes. Record the current and historical codes, and note the vehicle speed at the time of the fault, if available.
• Live wheel-speed data: With a scan tool, observe the wheel-speed sensor signals from all four wheels at rest and during slow rotation. Look for one wheel with zero, stuck, or erratic values, or large discrepancies between wheels.
• Vehicle speed vs. wheel speeds: Compare the vehicle speed signal (VSS) or ABS module speed to each wheel's speed reading. Inconsistent correlation suggests sensor or signal processing issues.
• Power and grounding: Check ABS module power supply and ground integrity. A weak voltage supply or poor ground can cause intermittent sensor readouts.
• Wiring and connectors: Visually inspect harnesses, connectors, and the area near each wheel for damaged insulation, corrosion, pin push-in at connectors, or loose grounds.
• Sensor and tone-ring condition: Inspect wheel-speed sensors for physical damage, contamination (dirt/oil), or mechanical interference. Inspect the tone ring or reluctor ring for chips, corrosion, missing teeth, or misalignment.
• Vehicle-specific notes: Some OEMs place the fault in the signal path from a particular wheel (e.g., left-front), while others log a general wheel-speed circuit fault. Verify with OEM service data for the vehicle.

Probable Causes

Note: The following probabilities are approximate, ASE-field-proxy estimates intended to guide priority in diagnostics. They do not come from (not available ). Use them as starting points and adjust based on vehicle make/model and observed data.

• Faulty wheel speed sensor (WSS) or sensor signal loss: ~40-50%
  • Reason: The WSS is the most common source of wheel-speed signal faults; a failed or contaminated sensor often yields a loss or irregular reading reflected as C0117.
• Damaged or degraded wiring/connector in the wheel-speed sensor circuit: ~25-30%
  • Reason: Damaged insulation, pin corrosion, or poor connector fit can create intermittent or perpetual signal loss without necessarily damaging the sensor itself.
• ABS/ESP control module or signal conditioning fault: ~10-15%
  • Reason: Although less common, a fault in the ABS/ESP module or its signal processing can present as a wheel-speed input fault.
• Damaged tone ring/reluctor ring or misalignment (sensor alignment issues): ~5-10%
  • Reason: A damaged or misaligned tone ring can cause erratic sensor readings, producing C0117-type faults.
• Electrical grounds or power supply issues affecting sensor circuits: ~5-10%
  • Reason: Inadequate grounding or low supply voltage can cause sensor signal degradation or dropout, mimicking a sensor fault.
• Other miscellaneous causes (e.g., intermittent CAN bus communication issues or manufacturer-specific interpretations): variable, typically low likelihood relative to the main causes above.

Notes on definitions and cross-references

• OEM definitions of C0117 can vary. Always confirm with factory service information for the specific vehicle to determine whether C0117 denotes a left-front sensor input fault, a general wheel-speed circuit fault, or another chassis-related wheel-speed criterion.
• Standard OBD-II classifications place C codes in the chassis category, associated with ABS/traction-control-related signals.
• For standard code reference conventions, GitHub definitions and repositories commonly align with the P/B/C/U code family and their general scopes (C codes = chassis/ABS). Use those as a cross-check, but rely on OEM data for exact code wording.

Diagnostic Approach

1) Confirm the fault and gather data

• Retrieve C0117 and any related ABS/ESP codes.
• Note freeze-frame data: vehicle speed, wheel speeds, and any other sensor readings at the time of the fault.

2) Visual inspection and basic checks

• Inspect all wheel-speed sensor harnesses and connectors at each wheel for damage, corrosion, or loose connections.
• Check for obvious mechanical interference with the sensor (e.g., debris, mud, or a foreign object near the sensor or tone ring).

3) Check wheel-speed sensor signals (live data)

• With the vehicle safely supported and at a low speed or wheel off the ground if needed, observe live wheel-speed data for all four wheels.
• Look for a wheel with zero or erratic speed data, or a wheel that does not respond as it spins.

4) Inspect the wheel-speed sensor and tone ring

• If a single wheel shows abnormal data, inspect the sensor for debris or damage; verify that the tone ring is intact and properly mounted.
• Spin the wheel by hand and watch the sensor output if the test setup allows.

5) Verify power and grounding to ABS module

• Check battery voltage, stability, and the ABS module's power and ground continuity. A weak supply can cause false readings or intermittent faults.

6) Electrical continuity and resistance checks

• Measure resistance of the suspect wheel-speed sensor per OEM specifications (many WSS have a specified resistance range; out-of-range values indicate a defective sensor).
• Inspect the wiring path for resistance/shorts to ground or to power.

7) Sub-system tests if needed

• If wheel-speed sensor and wiring appear sound, test the ABS/ESP module by monitoring its inputs and outputs under controlled conditions; check for related faults in the module's "live data" or "tests" screen as available on the scan tool.

8) Road test and recheck

• After repairs, perform a controlled road test to verify that wheel-speed signals are now consistent and the ABS/ESP lights do not return.
• Confirm that no additional codes reappear after clear and drive cycles (note that some ABS subsystems may require several drive cycles to reinitialize).

9) Post-repair verification

• Re-scan for codes after a drive cycle.
• Confirm all four wheel-speed signals are within expected ranges and that the vehicle's stability system remains available for use.

Repair Options

• Replacing a faulty wheel-speed sensor
  • Replacing the sensor at the affected wheel(s) is the most common fix when the sensor is physically damaged, contaminated, or producing out-of-range readings.
• Replacing or repairing wiring/connector
  • If the fault is traced to wiring or a connector (frayed insulation, corrosion, poor pin contact), repair or replacement of the wiring harness or the connector is warranted. Use OEM-compatible connectors and protect against future damage.
• Replacing the tone ring or correcting alignment
  • If the tone ring is damaged or misaligned, replacement of the tone ring or wheel hub assembly (depending on vehicle design) may be required; ensure proper gap and alignment during reassembly.
• ABS/ESP module service
  • If the fault lies within the ABS/ESP module (rare but possible), module repair or replacement may be necessary. This typically requires dealer-level diagnostics and programming.

Manufacturer Notes

• Some OEMs may list C0117 as a left-front wheel-speed sensor input fault or as a general "wheel-speed signal input circuit fault." Always verify the exact OEM definition from the vehicle's service information to avoid misdiagnosis.
• In some vehicles, additional ABS/ESP or body-control-related codes may accompany C0117; address all related codes in the diagnostic sequence for comprehensive system integrity.

Summary

• Start with a methodical check of the wheel-speed sensor signals, wiring, and tone ring for the suspect wheel, then verify ABS module health and power/ground integrity. Replace the faulty sensor, repair wiring or tone ring as needed, and re-test to confirm no reoccurrence of C0117. Always corroborate the exact OEM definition of C0117 for the vehicle you're working on, as the fault wording and target circuit can vary by manufacturer.

This diagnostic guide was generated using verified reference data:

• Wikipedia Technical Articles: OBD-II

Content synthesized from these sources to provide accurate, real-world diagnostic guidance.

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