C0118 is a chassis diagnostic trouble code that signals a problem affecting systems used by antilock and stability control functions, typically related to wheel-speed or wheel-speed signal integrity. It is a system-level classification from the chassis group and does not by itself identify a single failed part or a precise wheel location. You should treat C0118 as an indication that a wheel-speed or related chassis circuit is reporting out-of-range, implausible, or lost data to the vehicle control networks and require measured verification before any part replacement.
What Does C0118 Mean?
At the SAE J2012 level C0118 is a chassis code describing a fault in a circuit or data path used by Anti-lock Braking System (ABS) and Electronic Stability Control (ESC) functions. This guide follows SAE J2012 formatting; standardized DTC descriptions are published in the SAE J2012DA digital annex. The code identifies a symptom observed by chassis control modules, not a guaranteed component failure.
C0118 is shown here without a Failure Type Byte (FTB). An FTB (a hyphen suffix like “-1A”) would provide a subtype that narrows the failure mode (for example, short-to-voltage, short-to-ground, or intermittent), but that extra detail is not present for this base code. Exact component or pin-level meanings can vary by make, model, and year; confirm by checking wiring/connectors, sensor plausibility, power and ground, and Controller Area Network (CAN) or Local Interconnect Network (LIN) messages with a scan tool and basic bench multimeter tests.
Quick Reference
- Code group: Chassis — wheel-speed / wheel-circuit symptom
- Systems affected: Anti-lock Braking System (ABS), Electronic Stability Control (ESC)
- Typical symptoms: warning lamp, reduced stability/ABS function, degraded braking performance
- First checks: scan for freeze-frame, Mode 06, and live wheel-speed data
- Primary tests: wiring continuity, power/ground, signal waveform, CAN/LIN message presence
- Repair approach: test-driven — confirm failed circuit or module before replacement
Real-World Example / Field Notes
Field note 1 — Intermittent ABS lamp after a road salt season: commonly associated with corroded harness connectors at a wheel arch. Technician approach: reproducible symptom when turning steering lock; confirm by wiggling suspect harness while watching live wheel-speed values and checking for a lost or noisy signal. If live data drops to zero or shows rapid noise spikes during wiggle testing, inspect and repair the connector or wiring and confirm stable data before replacing sensors or modules.
Field note 2 — Single wheel speed shows implausible value: one possible cause is a sensor air gap or debris on the tone wheel. Procedure: measure AC or VR signal (or frequency/voltage for active sensors) at the sensor harness while rotating the wheel by hand; compare to the other wheels. If the waveform is absent or severely attenuated at the sensor connector but healthy further upstream, suspect harness/connector damage. If the sensor waveform is bad at the sensor, replace the sensor after confirming pin power/ground where applicable.
Field note 3 — Multiple ABS/ESC modules log C0118 with no obvious sensor failure: often associated with network message loss. Use a capable scan tool to verify Controller Area Network (CAN) or Local Interconnect Network (LIN) message presence for wheel-speed signals and check module supply voltages and grounds. If other modules show communication errors, prioritize power/ground and bus integrity tests before chasing individual sensors.
DISPLAY_LABEL: Chassis Circuit Fault – Wheel Speed/ABS Signal
Symptoms of C0118
- Pulsation — Brake pedal pulsation or unexpected ABS modulation during low-speed stops that the driver may feel as judder.
- Warning Light — Anti-lock Braking System (ABS) warning lamp or traction control indicator illuminated on the dash.
- Loss of Function — Partial or complete loss of ABS/ESC/TCS interventions under braking or cornering, depending on vehicle fail-safe behavior.
- Inconsistent Speed — Erratic or implausible wheel speed readings visible via a scan tool or freeze-frame data while driving.
- Noisy Sensor — Intermittent sensor signal noise or dropout on a scope or scan tool live data stream.
Common Causes of C0118
Most Common Causes
Faults most often point to wiring, connectors, or signal issues related to a wheel speed sensor circuit or its local module. Typical patterns include corroded or loose connector pins, chafed wiring harnesses near suspension or steering components, poor ground or supply to the sensor/module, and intermittent sensor-to-module signals. Many manufacturers implement wheel speed sensors and wheel module logic differently, so the exact circuit node and expected signal can vary by make, model, and year. Confirm the implementation with the vehicle wiring diagram and basic electrical/network testing before replacing components.
Less Common Causes
Less frequently the cause can be a failed sensor that shows out-of-spec resistance or no output when rotated, a local wheel module or ABS control unit internal fault, or Controller Area Network (CAN) / Local Interconnect Network (LIN) communication errors that mask a valid sensor signal. Software or calibration issues are possible but should be considered only after electrical and network tests rule out wiring and power/ground problems.
Diagnosis: Step-by-Step Guide
Tools: automotive scan tool with ABS/ESC capabilities and Mode $06 access, digital multimeter, oscilloscope (or frequency/AC meter), wiring diagrams, back-probing pins or breakout adapter, wiring continuity tester, insulated probe set, mechanic’s mirror and light, and a safe vehicle lift or hoist.
- Verify the concern: record driver complaints, capture when the ABS/traction light came on, and note any freeze-frame data from the scan tool.
- Collect data: connect a scan tool, read freeze-frame and live wheel speed data, record sensor values at known speeds, and check Mode $06 or manufacturer live tests for plausibility.
- Evaluate likely causes: compare live data to expected behavior—look for one wheel showing zero, stuck, or wildly fluctuating values versus others; consult wiring diagram to locate sensor circuit paths.
- Power/ground checks: with ignition on, measure reference voltage and ground at the sensor connector (back-probe); a missing reference or high ground resistance confirms wiring/connector fault potential.
- Signal test: spin the wheel by hand or drive at low speed while monitoring the sensor signal with an oscilloscope or frequency/AC meter; absence or unreadable waveform points to sensor or open circuit.
- Continuity and resistance: isolate the circuit and check continuity/resistance between sensor connector and module connector; an open or short to chassis indicates harness damage. Repair if confirmed.
- Wiggle and inspect: with connector connected, wiggle harness and rotate steering/suspension through range while watching live data for intermittent changes—this locates chafe or connector issues.
- Network checks: verify Controller Area Network (CAN) or Local Interconnect Network (LIN) health using the scan tool; inconsistent module responses or bus errors may mimic sensor faults and require bus troubleshooting.
- Confirm and rectify: when a test (open/short, missing supply, implausible waveform) identifies the root cause, perform the targeted repair—repair wiring, replace the sensor, or service the module as proven by tests.
Professional tip: never replace a wheel speed sensor or ABS module based solely on a code. Use scope and power/ground tests to prove where the fault originates; a shop that skips electrical verification often wastes labor and parts. After repair, always clear codes and confirm correct live-data behavior and that ABS/ESC self-tests pass on a road test.
DISPLAY_LABEL: Chassis Circuit Fault (Brake/Traction Systems)
Possible Fixes & Repair Costs
Repairs for C0118 center on electrical verification and targeted repairs; never replace parts without confirming failure. Low-cost fixes typically address connector cleaning, terminal repair, or a short wiring splice found by continuity checks. Typical repairs include sensor replacement or harness repair after a failed signal plausibility test or open/short confirmation. High-cost scenarios involve module replacement or multi-point wiring harness replacement when diagnostic testing shows internal module faults or extensive wiring damage.
- Low — $75–$250: justified when visual inspection and continuity checks show a corroded connector or pin that restores proper signal after cleaning and secure retermination.
- Typical — $250–$900: justified when bench or in-vehicle signal tests show a sensor or a shorted/ open harness segment; replacement or splice repair is confirmed by restored voltage/signal and cleared codes.
- High — $900–$2,400+: justified when the control module requires replacement or reprogramming after CAN/LIN bus tests show module-side faults or intermittent internal failures that persist after wiring repairs.
Cost factors: labor rates, diagnosis time, parts (sensor vs. module), vehicle accessibility, and programming needs. What justifies each repair: continuity and resistance measurements for wiring, stable reference voltage and ground at the connector, plausibility on the scanner, and successful post-repair verification (clear codes, confirm live data, road test). If a recommended repair does not follow a confirmatory test, treat it as unverified and return to testing.
Can I Still Drive With C0118?
You may be able to drive short distances, but proceed with caution. C0118 is a chassis-related circuit fault often associated with braking/traction systems like the Anti-lock Braking System (ABS) or Electronic Stability Control (ESC). Depending on the vehicle, these systems may be disabled or operate degraded, increasing stopping distance and reducing stability control during evasive maneuvers. Confirm system availability with a scan tool and perform basic brake tests at low speed in a safe area before normal driving.
What Happens If You Ignore C0118?
Ignoring C0118 risks degraded brake assist and stability interventions, unpredictable system behavior, and potential escalation from an intermittent wiring fault to a complete failure. That may leave you without ABS/ESC support when you need it most and can lead to higher repair costs later if wiring damage worsens.
Related Codes
- C0194 – Chassis Wheel Speed Signal Plausibility
- C0193 – Traction Control Torque Request Signal Range/Performance
- C0192 – Chassis Wheel Speed Signal Plausibility
- C0191 – Traction Control Torque Request Signal Low
- C0190 – Traction Control Torque Request Signal
- C0189 – Brake Wheel Speed Signal Plausibility
- C0188 – Stop Lamp Switch Circuit Range/Performance
- C0187 – Brake Wheel Speed Signal Plausibility
- C0186 – Chassis Wheel Speed Sensor Circuit Fault
- C0185 – Chassis Wheel Speed Signal Plausibility
Key Takeaways
- SAE J2012 formatting defines C0118 at the chassis circuit level; manufacturer definitions can vary.
- Use a test-driven approach: verify symptom, collect data, then measure power/ground, continuity, and signal plausibility.
- Wiring, connectors, and CAN/LIN communication are common root causes; confirm before replacing sensors or modules.
- Post-repair verification (clear codes, live-data checks, road test) is mandatory to confirm a successful fix.
- Costs vary widely; diagnostic confirmation narrows repair scope and prevents unnecessary parts replacement.
Vehicles Commonly Affected by C0118
- Commonly seen on passenger cars with advanced chassis controls—manufacturers often reported: Ford, General Motors, Toyota, Honda, and BMW models.
- Often reported on vehicles equipped with ABS, ESC, and traction control systems; occurrences may be higher in older vehicles with corrosion-prone connectors or in models using hub-speed sensors and multiple networked modules.
- Definition and impacted components can vary by make, model, and year; always confirm with wiring diagrams and in-vehicle testing for the specific vehicle.
FAQ
Can a bad wheel speed sensor cause C0118?
Yes—one possible cause is a wheel speed sensor failure, but C0118 is a chassis circuit-level code and does not guarantee a single failed sensor. Confirm with tests: measure sensor resistance and AC voltage while spinning the wheel, check reference voltage and ground at the sensor connector, and verify plausibility against other wheel speed readings on a scanner. Repair is justified only when measurements fall outside manufacturer-specified ranges or a wiring fault is confirmed.
Can a wiring harness or connector problem set C0118?
Absolutely. Wiring and connector issues are common causes. Perform visual inspection for corrosion, broken strands, or pin damage and use a multimeter for continuity and voltage drop tests. A pin-to-pin short, open, or high-resistance connection that resolves after repair justifies connector repair or harness replacement. Always confirm by restoring proper voltages and verifying live data and fault code clearance before finalizing the repair.
Is module replacement often required for C0118?
Module replacement is less common and should be a last resort. Prioritize power, ground, wiring, and network message checks (CAN/LIN) using a capable scanner and oscilloscope if available. Replace a module only when bench tests or manufacturer diagnostics indicate internal module failure or when the module fails to communicate despite verified correct wiring, power, and ground. Documentation of failed tests must support module replacement.
How do I test CAN or LIN communication for this code?
Start with a scan tool to confirm module presence and message frequency. Check for voltage at bus lines with the ignition on, inspect termination resistances, and use a scope to view differential CAN signals or LIN waveform quality. Intermittent or absent messages that correlate with the fault support communication-related repairs. Repair is justified when bus wiring or termination faults are found or when a module is non-responsive after confirming healthy bus signals.
Will clearing the code make C0118 go away permanently?
Clearing the code can remove the stored DTC temporarily, but it does not fix the root cause. If the underlying wiring, sensor, or communication fault remains, the code will likely return. Use clearing as part of the verification step after a confirmed repair: clear codes, re-run diagnostics, and perform a road test to ensure the fault does not reappear and that related system monitors and functions operate correctly.