C0040 Right front wheel speed sensor circuit (GM) or brake lamp switch (Honda)

Right front wheel speed sensor circuit

C0040 in short

On Chevrolet and other GM vehicles, C0040 means the right front wheel speed sensor signal is faulty, and ABS and stability control switch off. On Honda, owner complaints show it as a brake lamp switch fault. Brakes need inspecting soon; a hub or sensor is the usual GM fix.

The code has two meanings among the makes we could source. On GM vehicles it belongs to the wheel speed sensor family (C0035, C0040, C0045, C0050); C0040 is the right front sensor. Saab service information on a GM-based car gives the setting conditions and says the brake module disables ABS, traction control, stability control and hill start assist for the ignition cycle.

Owner complaints on Chevrolet Colorado, Malibu and other GM vehicles quote dealer invoices that found the right front hub and sensor with an intermittent open circuit or a dropping signal and replaced them. GM bulletin PIT3460N, quoted by an owner, lists C0035, C0040, C0220 and C0221 together with an ABS light; the bulletin itself was not read.

On Honda, two owner complaints quote a technician and a dealer giving C0040 with a -12 or -62 suffix as a brake switch fault. Other makes may use the code differently, and we have not verified them.

Pick your make

C0040 is a manufacturer-specific code: its meaning depends on who built the car.

Other makes: meaning not verified. Check with a scan tool that reads manufacturer definitions.

Most likely causes

  1. Right front wheel speed sensor or hub (GM)

    Supported by vehicle data
    Why it ranks here
    Dealer invoices quoted in Chevrolet complaints replaced the right front hub and sensor for C0040.
    What would change this
    Rises if the sensor signal drops out or the wiring at the hub is damaged. Falls if the signal is clean when the wheel spins.
    How to test the brake system control module (abs module)

  2. Sensor wiring, connector or water in the control module connector

    Common general cause
    Why it ranks here
    Saab's checks cover damage, contamination, installation and circuit voltage and resistance; a GM bulletin quoted by an owner groups several wheel speed codes under one ABS light.
    What would change this
    Rises if wiring is rubbed or the connector is wet or corroded. Falls if circuits test normal.

  3. Brake lamp switch stuck or failed (Honda)

    Supported by vehicle data
    Why it ranks here
    Honda readouts quoted in two complaints give the code as a brake lamp switch fault.
    What would change this
    Rises if brake lights stay on or the brakes drag. Falls if the brake lights work normally.

What to test first

Start at step 1. Each result tells you what it means and where to go next.

  1. Read the full code with its suffix and the live wheel speed data, and note the make-specific meaning.

    Low riskTool: scan tool with ABS data

Symptoms

  • ABS light and traction or stability control light on
  • ABS activating on its own at low speed
  • Brake lights staying on or a hot wheel after driving (Honda reports) Gets more serious: stop and have it checked.
  • Brake or ABS warning light on together with the stability control light Gets more serious: stop and have it checked.

How to fix

This is a safety-critical system, so we explain the code but don't give repair steps. Have it inspected by a qualified technician.

Parts and cost context

  • Brake system control module (ABS module):On GM trucks the sensor is often part of the hub assembly. Labor varies; get a quote.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Chevrolet

  • 2004–2005 · Colorado

    Supported by vehicle data

    Owner complaints quote a dealer invoice replacing the right front hub and sensor for C0040, and GM bulletin PIT3460N for ABS light with C0035, C0040, C0220 or C0221. The bulletin was not read.

Honda

No curated relationships for C0040 yet.

All ABS, traction and stability control codes

C0040 questions

Does C0040 always mean a wheel speed sensor?

On GM vehicles yes, the right front one. On Honda, owner complaints quote it as a brake lamp switch fault, so read the suffix and make-specific data.

Sources and review

  1. DTC C0035, C0040, C0045, or C0050 (9-5 9650 2011) — Saab Workshop Information System (SaabWISonline mirror)
  2. NHTSA complaint ODI 11191073: 2018 Honda CR-V hot left front brake — NHTSA Office of Defects Investigation
  3. NHTSA complaint ODI 10273914: 2005 Chevrolet Colorado ABS light — NHTSA Office of Defects Investigation
  4. NHTSA complaint ODI 10150643: 2004 Chevrolet Colorado ABS dealer invoice — NHTSA Office of Defects Investigation
  5. NHTSA complaint ODI 10629708: 2009 Chevrolet Malibu traction control message — NHTSA Office of Defects Investigation
  6. NHTSA complaint ODI 11645269: 2020 Honda Pilot warning lights and brakes — NHTSA Office of Defects Investigation
Last reviewed
Written by
Saurabh K.
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This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error

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