C0040 on 2015-2019 GMC Canyon: Right Front Wheel Speed Sensor Causes and Fixes

What's Unique About the 2015-2019 Gmc CANYON

For the 2015-2019 GMC Canyon and its sibling, the Chevy Colorado, the C0040 code is frequently traced back to one of two main issues. The first is a failure of the short wiring harness that connects the sensor to the main chassis harness. 🎬 Watch: How to inspect the common harness failure point. The second, documented in GM Technical Service Bulletin #PIT5499B, is water leaking into the main Electronic Brake Control Module (EBCM) connector, causing corrosion and signal faults. This makes checking both the wheel-end wiring and the main module connector on the driver's side frame rail essential during diagnosis. 🎬 See a professional diagnostic walkthrough using a Picoscope. A third very common issue is the magnetic reluctor/tone ring, which is integrated into the wheel bearing, flaking off or breaking, causing a signal dropout.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• ABS warning light is on
• StabiliTrak or Traction Control warning light is on
• "Service Trailer Brake" message on the driver information center
• ABS system may activate unnecessarily at low speeds, causing a grinding or pulsating brake pedal
• Cruise control may be disabled

Most Likely Causes

1. Damaged or Failed Right Front Wheel Speed Sensor Harness 🔴 High Probability → Shop ABS Wheel Speed Sensor The wiring harness is exposed to the elements, suspension movement, and debris, which can cause wires to break or chafe over time. This is a very common failure point on this platform, often failing before the sensor itself.
   How to confirm: Visually inspect the harness from the wheel hub up into the fender well for any signs of damage, fraying, or corrosion at the connectors. Check for continuity on each wire with a multimeter. A common failure point is where the harness is clipped to the frame or suspension components.
   Typical fix: Replace the short wheel speed sensor wiring harness. This part is sold separately from the sensor itself. The ACDelco GM Original Equipment part number is 84153436.
   Est. part cost: $25-$75
2. Failed Right Front Wheel Hub Bearing Assembly (Damaged Tone Ring) 🔴 High Probability → Shop Hub Assembly On this truck, the magnetic reluctor ring (or tone ring) that the sensor reads is an integral part of the wheel hub bearing assembly. It is common for a piece of this magnetic ring to flake off or break, creating a gap in the signal that the sensor reads. This causes an erratic signal and triggers the C0040 code, even if the bearing itself feels tight.
   How to confirm: With the vehicle raised, spin the wheel by hand while observing the tone ring with a borescope or by removing the sensor. Look for any missing chunks or flaked-off sections of the dark magnetic ring on the inboard side of the hub. A diagnostic scope can also reveal a bad spot in the tone wheel's signal as the wheel is spun.
   Typical fix: Replace the entire front wheel hub bearing assembly. The hub bolts should be torqued to 133 lb-ft. The GM OEM part number is 84427124.
   Est. part cost: $150-$300
3. Water Intrusion at EBCM Connector 🟡 Medium Probability As noted in TSB #PIT5499B, the main connector for the Electronic Brake Control Module (EBCM), located on the driver's side frame rail, can be susceptible to water intrusion. This leads to corrosion on the pins for the wheel speed sensor circuits, causing this code and often others (like C0035).
   How to confirm: Locate the EBCM on the driver's side frame rail below the cab. Disconnect the large main electrical connector and inspect for any signs of moisture, green or white corrosion, or damaged pins.
   Typical fix: Clean the connector and module pins with a specialized contact cleaner if corrosion is minor. Apply dielectric grease before reconnecting to prevent future moisture. If damage is severe, the connector pigtail or affected terminals may need to be replaced. The source of the water leak should also be identified and sealed.
   Est. part cost: $50-$150 for a connector pigtail
4. Failed Right Front Wheel Speed Sensor ⚪ Low Probability → Shop ABS Wheel Speed Sensor While the sensor itself can fail, it is less common than wiring or bearing/tone ring issues on this platform. Often, the sensor is replaced when the actual fault was in the wiring harness or the tone ring. The GM OEM part number for the sensor is 84375752.
   How to confirm: Use a scan tool with live data capability to monitor the right front wheel speed while driving. If the reading is zero or erratic while the other wheels read correctly, and the wiring/hub are confirmed good, the sensor is likely faulty. One can also check the sensor's resistance with a multimeter.
   Typical fix: Replace the right front wheel speed sensor. This sensor is bolted to the steering knuckle.
   Est. part cost: $40-$90

Rare But Worth Checking

• Faulty Electronic Brake Control Module (EBCM): → Shop ABS Control Module This is rare and should only be considered after all other possibilities (sensor, wiring, hub) have been definitively ruled out. An EBCM failure will often be accompanied by multiple other trouble codes (e.g., C0035, C0045) or communication codes like U0121.

Diagnosis Steps

1. Read the trouble codes with an ABS-capable OBD-II scanner. Note any symptom bytes, like '5A'.
2. Visually inspect the right front wheel speed sensor wiring harness for any obvious signs of damage, chafing, or corrosion from the wheel hub to its connection point in the fender well.
3. CRITICAL: Inspect the main electrical connector on the Electronic Brake Control Module (EBCM) on the driver's side frame rail for any signs of water intrusion or corrosion, per TSB #PIT5499B.
4. Use a scan tool to view live data for all four wheel speed sensors. Drive the vehicle and observe if the right front sensor reading drops out, is erratic, or doesn't match the other sensors.
5. Safely raise and support the front of the vehicle. Check the right front wheel for any play by grabbing it at the top and bottom and trying to rock it. While excessive play indicates a bad wheel bearing, the tone ring can fail even without noticeable play.
6. Remove the wheel speed sensor and use a borescope to inspect the magnetic tone ring on the hub assembly. Rotate the hub and look for missing chunks, cracks, or flaked-off sections.
7. If no obvious issues are found, use a multimeter to test the continuity and resistance of the wiring harness between the sensor and the EBCM.
8. If the wiring and hub/tone ring are confirmed to be good, the final step is to replace the wheel speed sensor itself.

Parts You'll Likely Need

• Front Wheel Speed Sensor Harness (OEM #84153436) — This is a very frequent point of failure due to its exposure to movement and the elements.
  Trusted brands: ACDelco, Dorman
  OEM price range: $50-$90
  Aftermarket price range: $25-$50
• Front Wheel Bearing and Hub Assembly (OEM #84427124) — The integrated magnetic tone ring is a known failure point, flaking off and causing an erratic signal. The hub is replaced as a complete unit.
  Trusted brands: ACDelco, MOOG, Timken, Delphi
  OEM price range: $250-$400
  Aftermarket price range: $150-$300
• Front Wheel Speed Sensor (OEM #84375752) — Though less common than wiring or hub failure, the sensor itself can fail and is often replaced during a hub replacement.
  Trusted brands: ACDelco, Delphi, Bosch
  OEM price range: $60-$100
  Aftermarket price range: $40-$90

Related Codes That Often Appear With This One

• C0035 — This code is for the Left Front Wheel Speed Sensor circuit. Seeing it with C0040 could point towards a systemic issue like water intrusion at the EBCM connector affecting multiple circuits, as mentioned in TSB PIT5499B.
• U0121 — This code indicates a loss of communication with the ABS control module. It can appear alongside C0040 if the EBCM is failing or has a severe power/ground issue, often related to the water intrusion problem described in TSB PIT5499B.
• C0040 5A — The '5A' is a symptom byte indicating 'Plausibility Failure'. This often points to a problem with the signal itself, such as from a damaged tone ring on the wheel bearing, rather than an open or shorted wire.

Technical Service Bulletins (TSBs) & Recalls

• PIT5499B: Advises technicians to inspect the Electronic Brake Control Module connector for water intrusion when various ABS codes, including C0040, are present. Also suggests inspecting the G400 ground conduit.

Platform-Specific Known Issues

• Water Intrusion at EBCM Connector (TSB PIT5499B): A known issue documented in GM TSB #PIT5499B involves water intrusion into the Electronic Brake Control Module (EBCM) connector, located on the driver's side frame rail. This causes corrosion and can trigger C0040 and other related ABS codes.
• Flaking/Broken Magnetic Tone Ring: A very common failure on this platform is for the magnetic tone ring, which is part of the wheel hub assembly, to break or have pieces flake off. This creates a gap in the signal read by the sensor, triggering a C0040 code even if the bearing feels solid.

Mechanic-Grade Diagnostic Values

• Wheel Speed Sensor Resistance — expected: 800 - 2,500 Ohms. Failure: Resistance is infinite (open circuit), very low, or shorted to ground.
• Wheel Speed Sensor AC Voltage Output — expected: 0.5V - 2.0V AC (when spinning wheel by hand). Failure: No AC voltage is produced, or the voltage is significantly lower than expected, indicating a failed sensor.
• Wheel Speed Sensor Harness Voltage (at sensor connector, key on) — expected: Approximately 12 Volts on the power supply wire.. Failure: Voltage is not present, indicating a fault in the EBCM or the wiring harness.

Hidden / Shadow Codes Worth Checking

• C0040 06: Indicates the EBCM has detected low voltage or an open in the right front wheel speed sensor circuit. This points towards a broken wire or bad connection. (see via Dealer-level scan tool like GM GDS2 or high-end professional scanner.)
• C0040 0F: Indicates the EBCM has detected an erratic signal from the right front wheel speed sensor. This is often caused by a damaged tone ring or a failing sensor. (see via Dealer-level scan tool like GM GDS2 or high-end professional scanner.)
• C0040 18: Indicates the signal amplitude from the right front wheel speed sensor is below the minimum threshold. This can be caused by an excessive air gap or a weak sensor. (see via Dealer-level scan tool like GM GDS2 or high-end professional scanner.)
• C0040 5A: Indicates the signal from the right front wheel speed sensor is not plausible. This is a very common symptom byte for a damaged or flaking magnetic tone ring on the wheel bearing. (see via Dealer-level scan tool like GM GDS2 or high-end professional scanner.)

Scan Tool Commands That Help

• GM GDS2 or equivalent professional scanner: Automated Bleed Procedure — This function is required after replacing the EBCM or the entire brake pressure modulator valve (BPMV) assembly to properly bleed air from the internal passages of the ABS unit.
• GM GDS2 or equivalent professional scanner: Module Setup/Programming — If the Electronic Brake Control Module (EBCM) is replaced, it must be programmed with the vehicle's VIN and specific configuration using a scan tool. A new module will not function correctly until this is done.

Wiring & Ground Locations

• G105 — Located on the left side of the engine compartment, near the Electronic Brake Control Module (EBCM).. This is a primary ground point for the EBCM. A poor connection at G105 can cause various ABS faults, including wheel speed sensor codes, due to improper module function.
• Right Front Wheel Speed Sensor Connector — At the wheel hub, connecting the sensor to the short pigtail harness that runs up into the fender well.. This 2-pin connector is exposed to the elements and is a common point for corrosion or wire damage, directly interrupting the sensor signal.
• EBCM Connector (X1) — Large electrical connector on the Electronic Brake Control Module, located on the driver's side frame rail.. As per TSB #PIT5499B, this connector is prone to water intrusion. The right front wheel speed sensor signal and power wires terminate here. Corrosion on these specific pins will cause a C0040 code.

Real Owner Repair Stories

• YouTube video from '2015-2022 Chevy colorado,GMC canyon stabilitrac,abs diagnostic' (2017 Chevrolet Colorado (93,000 miles)) — ABS and Stabilitrak lights on, humming noise.
  ❌ Tried (didn't work) Initial test drive did not reveal an obvious wheel bearing noise.
  ✅ What actually fixed it The problem was a damaged magnetic encoder ring on the wheel bearing. A piece of the magnet had broken off, causing an intermittent and implausible signal (Code C0035 5A, the left-side equivalent of C0040 5A). The fix was to replace the wheel bearing/hub assembly and the wheel speed sensor.
• YouTube video from 'GMC Canyon - Stabilitrak ABS Traction control C0040' (GMC Canyon (year not specified)) — ABS, Stabilitrak, and Traction Control lights on. Scan tool showed C0040 5A 'not plausible'. Freeze frame data showed the right front wheel speed at 1 mph while other wheels were at 16 mph.
  ❌ Tried (didn't work) The technician noted that the bearing felt fine with no play.
  ✅ What actually fixed it The technician found a 'dry spot' or damaged section on the magnetic tone ring integrated into the wheel bearing. After replacing the wheel bearing and hub assembly, the live data on the scan tool showed a smooth and consistent signal when spinning the wheel.