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DTC codes / U04xx · Invalid data received from a module / U0418

U0418Invalid Data Received From Brake System Control Module

U0418 means the vehicle's main computer, usually the engine control module (ECM), has received invalid or missing data from the brake system control module over the controller area network (CAN) bus. The ECM sets this code when the brake module's messages are absent, corrupted, or fail the expected checksum, so the ECM cannot trust the brake system's status.

SystemNetwork
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyProfessional
AreaInvalid data received from a module

Symptoms you may notice

  • Anti-lock braking system (ABS) warning light illuminated on the dashboard
  • Traction control or stability control warning light on, sometimes with a message such as 'Service StabiliTrak'
  • Red brake warning light on in some vehicles, especially if the brake module also stores its own fault
  • Speedometer, odometer, or cruise control behaving erratically because wheel-speed data is shared over the same network
  • Often no symptoms besides the warning light, with normal brake pedal feel and normal stopping performance
  • Intermittent warning lights that come and go, especially after rain, a car wash, or driving over rough roads

Common causes, most likely first

  1. Damaged, corroded, or loose wiring and connectors in the CAN bus circuit between the ECM and the brake system control module
  2. Low or unstable battery voltage, or a weak charging system, causing the brake module to drop offline intermittently
  3. Failed or failing brake system control module, including internal faults in its CAN transceiver
  4. Water intrusion into the brake module connector or into a harness splice, common in vehicles with modules mounted low in the engine bay or under the floor
  5. Aftermarket electronics, such as alarms, remote starters, or dash cameras, improperly spliced into the CAN wiring and disturbing the bus
  6. A separate fault stored in the brake module that prevents it from broadcasting valid data, such as a wheel-speed sensor or pump motor fault
  7. CAN bus termination or shield problems elsewhere on the network that corrupt messages before they reach the ECM

How to diagnose and fix it

  1. Scan all modules and record every stored code, then clear codes and test-drive to see whether U0418 returns immediately or only intermittently
  2. Inspect the brake system control module connector and the ECM connector for corrosion, pushed-out pins, or water intrusion, and check battery voltage and charging system output
  3. Perform a voltage-drop and resistance check on the CAN high and CAN low wires between the ECM and the brake module, looking for opens, shorts to ground, or shorts to power
  4. Check for aftermarket accessories spliced into the CAN wiring and remove or repair any improper connections
  5. Verify the brake module is communicating on the network with a scan tool that can view live module status, and check for any brake module internal codes that would explain the missing data
  6. If wiring and power are good, substitute a known-good brake system control module or perform module reprogramming as directed by the manufacturer's service information
  7. After repair, clear codes, perform any required module relearn or calibration, and road-test to confirm U0418 does not return

Why the brake module goes quiet on the network

  • U0418 is a communication code, not a hydraulic brake fault, so a car with a firm pedal and normal stopping power can still have this code and does not necessarily need brake hardware replaced.
  • A weak battery or a failing alternator is a common hidden cause because the brake module may reset or drop off the CAN bus during cranking or under load, setting U0418 without any wiring damage.
  • Water intrusion into a connector or a chafed harness behind a wheel well or under the floor is frequently missed, so a visual inspection in wet areas matters as much as electrical testing.
  • Aftermarket alarms, remote starters, and dash cameras spliced into CAN wiring are a frequent culprit on used vehicles, and removing the splice often clears the code without replacing any module.
  • The brake module may store its own codes, such as a wheel-speed sensor fault, that prevent it from sending valid data; diagnosing only the ECM side will miss the real cause.

Can I keep driving with U0418?

The vehicle is usually safe to drive because the base hydraulic brakes still work, but you should avoid towing, hard braking, or relying on stability control until the fault is repaired. If the red brake warning light is on or the pedal feels abnormal, stop driving and have the vehicle inspected promptly.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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