SAE J2012-classified chassis fault C0718 indicates a chassis-level wheel speed signal plausibility issue reported to a vehicle control module such as an antilock braking system (ABS) or electronic stability control (ESC) unit. This is a system-level description: it flags an implausible, inconsistent, or missing wheel-speed-related signal rather than naming a single failed sensor or exact location. Many chassis codes do not carry a universal component-level definition and can vary by make, model, and year, so test-driven electrical and network checks are essential before replacing parts.
What Does C0718 Mean?
This guide follows SAE J2012 formatting and uses standardized DTC wording; SAE publishes the common DTC structure and many standardized descriptions in the SAE J2012-DA digital annex. C0718 is presented here in that SAE-style framework as a chassis circuit-level fault tied to wheel speed signal plausibility.
The code is shown without a hyphen suffix (no Failure Type Byte). If an FTB were present (for example “-1A”), it would act as a subtype describing the specific failure mode or occurrence condition recorded by the control module. Interpretation of C0718 can vary by vehicle: it typically indicates a plausibility or performance condition with the wheel-speed input rather than a simple open or short.
Quick Reference
- System: Chassis wheel speed signal plausibility reported to ABS/ESC
- Common effect: ABS/ESC/traction control lamp, inconsistent speed readout
- Primary tests: wiring/connectors, sensor output waveform, power and ground, CAN message checks
- Typical causes: wiring or connector fault, sensor signal noise or loss, poor power/ground, CAN/vehicle network issues
- Repair approach: follow test-driven diagnosis; replace parts only after confirming failed component with measurements
- Safety: braking stability features may be reduced until fault is cleared and verified
Real-World Example / Field Notes
In the shop you may see an ABS lamp and a stored C0718 after a vehicle experienced intermittent ABS operation during low-speed maneuvers. A common field pattern is a module reporting an implausible wheel speed comparison — one wheel’s speed disagrees with others or with vehicle speed sensors derived from the transmission. In many cases the root cause proves to be intermittent wiring at a connector that allowed signal dropout under vibration; the sensor itself tested fine on the bench.
Another frequent observation: multiple technicians assume the wheel sensor has failed, but a quick scope check reveals a noisy or trimmed waveform caused by a corroded connector or shielding failure. In other vehicles, the code appears alongside CAN bus errors and is resolved only after repairing a bus short or restoring a ground that affected multiple nodes. Always confirm with waveform, voltage, and network message checks rather than replacing a module first.
SAE J2012-DA classifies C-codes as chassis circuit issues; C0718 is a chassis-level signal plausibility fault rather than a guaranteed failed part. The exact component or location tied to C0718 varies by make, model, and year, so you must verify with basic electrical and network testing before repairing. Start by checking wiring, connectors, power and ground, and message plausibility on CAN or Local Interconnect Network (LIN) where applicable. Treat this code as a disagreement or implausible reading in a wheel-speed-related circuit until tests narrow the cause.
Symptoms of C0718
- Warning Light ABS/ESC/TCS warning lamp or brake lamp illuminated on the dash.
- Pulsating Brake Unusual brake pedal behavior or unexpected ABS activation during normal braking.
- Speed Mismatch One or more wheel speed readings inconsistent with vehicle motion on a scan tool.
- Reduced Function Limited traction- or stability-control interventions or degraded system performance.
- Intermittent Fault appears or clears with vibration, steering movement, or temperature changes.
Common Causes of C0718
Most Common Causes
Wiring and connector faults are the most frequent causes: corroded pins, broken wires in harnesses near suspension, or pushed-out terminals producing intermittent or implausible wheel speed signals. Faulty wheel speed sensor elements or tone rings (commonly associated with wheel speed circuits) can produce readings that conflict with other speed inputs. Low or missing sensor supply voltage or poor module ground returns that alter signal levels are also common contributors.
Less Common Causes
Less commonly, internal processing or input-stage issues in an ABS/ESC control module (possible after all external inputs test good) or intermittent CAN/LIN bus errors causing message timing problems can manifest as C0718. Faulty drivetrain components that legitimately produce unexpected wheel speeds are possible but rare; confirm with data before assuming mechanical causes.
Diagnosis: Step-by-Step Guide
Tools: OBD-II scan tool with live data and freeze-frame, digital multimeter, oscilloscope (recommended), wiring diagrams, backprobe pins or breakout adapter, jumper wires, audible tone reader or hall sensor tester, basic hand tools, and a CAN/LIN message reader where available.
- Read the code and freeze-frame with a scan tool. Record recorded vehicle speed, axle speeds, and any related live data that show implausibility.
- Check for an FTB (failure-type byte) suffix in the stored code. If none, note that an FTB would indicate a subtype; treat the base code as shown.
- Visually inspect wiring and connectors for damage, corrosion, or chafing around wheel housings and suspension articulation points.
- With key on engine off, measure sensor supply voltage and ground at the harness connector. Compare to expected reference values from OEM documentation; low or missing supply indicates power/ground fault.
- Backprobe the sensor signal and view on an oscilloscope while spinning the wheel by hand. Look for a clean AC or digital waveform and amplitude consistent with other wheel signals; an implausible or noisy waveform supports sensor or tone-ring issues.
- Perform a wiggle test on the harness and connectors while watching live data for intermittent changes; this helps locate breaks under load/movement.
- Check resistance of sensor when specified; an open/short relative to expected ranges suggests sensor or short to battery/ground if out of range.
- Verify CAN/LIN health: check for error counters, missing messages, or bus voltage problems. Use a message reader to confirm consistent wheel speed messages from other modules.
- If wiring, power, ground, and sensor signals test good yet the fault remains, consider module input-stage evaluation per OEM guidance; document all tests before module replacement.
- Clear the code and perform a controlled road test while logging live data to confirm the fix; if the fault returns, repeat targeted testing on failed circuit elements.
Professional tip: Always compare the suspect wheel speed waveform or value to at least one known-good wheel on the same vehicle. Plausibility is relative—matching patterns between axles during the same test run is often the fastest way to separate wiring/connector faults from module-level problems.
Possible Fixes & Repair Costs
Low-cost fixes usually involve wiring or connector repairs when testing shows open, high resistance, or intermittent continuity on the related circuit. Typical repairs include sensor replacement or connector cleaning when bench or parasitic voltage tests show a failed sensor waveform or inconsistent signal. High-cost work includes extensive harness repair, junction box replacement, or module work if a confirmed CAN (Controller Area Network) bus fault or after external inputs test good and an internal processing or input-stage issue is suspected. Every repair should be driven by specific test results: voltage/ground verification, scope waveform plausibility, and continuity checks.
- Low: $40–$180 — just connector cleaning, terminal repair, or simple wiring splice confirmed by continuity and voltage tests.
- Typical: $180–$550 — sensor replacement or larger harness section repair justified by failed waveform, open/short findings, or sensor bench test failure.
- High: $550–$1,600+ — complex harness replacement, junction box or ABS/ESC module intervention after all external wiring, power, ground, and network tests pass.
Factors affecting cost: labor time to access components, whether multiple sensors or wiring runs are involved, specialist tools required for network diagnostics, and whether module programming or calibration is needed after a confirmed replacement.
Can I Still Drive With C0718?
You can often drive with this code, but you should do so cautiously. A chassis speed sensor plausibility fault commonly affects ABS, ESC (Electronic Stability Control), and traction control performance; those systems may be limited or disabled. If driving in dry, low‑risk conditions for short trips is necessary, keep speeds moderate and leave extra braking distance. Avoid heavy braking, slippery roads, or towing until you verify sensor signals, power/ground integrity, and network communication with a scan tool and basic scope checks.
What Happens If You Ignore C0718?
Ignoring the code can leave ABS/ESC/TCS functions degraded or inoperative, increasing stopping distances and loss-of-control risk in low-traction situations. Intermittent faults may worsen, making diagnosis harder and potentially causing additional wiring or module stress. Repairs often cost more the longer a problem persists, so verify power, ground, wiring, and signal plausibility promptly.
Related Codes
- C0767 – Brake Control Signal Plausibility (Chassis)
- C0766 – Tire Pressure Monitor System – High Tire Pressure
- C0765 – Wheel Speed Sensor Signal Plausibility - Chassis
- C0764 – Tire Pressure Monitor System – Low Tire Pressure (Right Rear)
- C0763 – Steering Sensor Signal Plausibility
- C0762 – Brake Pressure Signal Plausibility
- C0761 – Brake Pressure Signal Plausibility
- C0759 – Steering Assist Communication Fault
- C0758 – Tire Pressure Monitor Sensor Circuit Range/Performance
- C0757 – Steering Angle Signal Circuit Fault
Key Takeaways
- SAE J2012-DA defines this as a chassis-level speed sensor circuit plausibility issue; manufacturer interpretation can vary.
- Diagnosis must be test-driven: check power, ground, wiring, connector integrity, and signal waveforms before replacing sensors or modules.
- Network checks (CAN/LIN) and Mode $06/Live Data plausibility are essential when external tests appear normal.
- Only consider module internal issues after all external inputs and network segments test good.
Vehicles Commonly Affected by C0718
This fault is commonly seen on vehicles with integrated ABS/ESC networks and multiple wheel-speed sensors — often reported on European luxury cars, mainstream Japanese sedans, and light trucks with advanced stability systems. These platforms use distributed sensors, shared network buses, and complex harness routing, which raises the chance of connector corrosion, chafing, or CAN wiring issues. Interpretation and repair steps can vary by make, model, and year, so confirm with vehicle-specific wiring diagrams and network topology when diagnosing.
FAQ
Can I clear C0718 with a generic OBD-II scanner?
Yes, many generic OBD-II or ABS-capable scanners can clear the trouble code, but clearing does not diagnose the root cause. After clearing, you must re-test: inspect live data, perform a road test while watching wheel-speed sensor signals, and re-check for code return. If code returns immediately or intermittently, proceed to voltage/ground, continuity, and scope waveform checks to find the actual fault rather than relying on clears alone.
Is a replacement sensor always required for C0718?
No. Replace a sensor only when test results justify it: failed bench tests, no signal on a known-good power/ground, or bad waveform on a scope. If power, ground, and wiring continuity are out of tolerance or intermittent, repairing the harness or connector is the correct first step. Only after those tests pass and the sensor shows implausible output should you replace the sensor or consider module input-stage troubleshooting.
What tools do I need to diagnose this code effectively?
Essential tools: a quality scan tool with ABS/ESC and freeze-frame/Mode $06 data, a digital multimeter (DVOM), an automotive oscilloscope for wheel-speed waveforms, wiring diagrams, a backprobe kit, and basic hand tools. A breakout box or CAN-bus tester helps for network-level faults. These tools let you confirm power/ground integrity, measure sensor waveforms, and isolate wiring versus module or network issues in a test-driven way.
Can intermittent C0718 faults be found without a scope?
Sometimes you can find intermittents with careful wiggle tests, continuity checks while moving connectors, and by monitoring live data on a scan tool during a road test. However, many intermittent signal plausibility issues require an oscilloscope to capture waveform dropouts, noise, or timing errors. If intermittent signals aren’t visible with a scanner, use a scope to confirm signal quality before replacing components.
Can a repair shop or dealer handle this diagnosis for me?
Yes. A competent independent shop with the right scan tools and a scope can perform thorough wiring, signal, and network tests. Dealers have OEM wiring diagrams and manufacturer-specific procedures that may speed diagnosis, but they are not always necessary. Ask any shop if they will perform power/ground, continuity, and waveform tests and provide the measured evidence before replacing sensors or modules.