U0418

Code

Generic U — Network/User

Invalid Data Received From Brake System Control Module A

Brand: Generic

Type: U — Network/User

Views: UK: 75 EN: 227 RU: 109

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Page language: EN

Corrupted or malformed CAN/LIN messages from Brake System Control Module A
Poor power or ground to the brake module causing transmission errors
Damaged wiring or connectors on the vehicle network (CAN high/low) or module harness
Faulty Brake System Control Module A (internal software or hardware fault)
Module software mismatch after updates or replacement
Interference on the vehicle bus or excessive bus load

Read and record current freeze frame and all stored DTCs from all modules
Check for other U-codes indicating broader network issues (U0100, U0121, etc.)
Visually inspect ABS module connector and wiring for corrosion, damage or loose pins
Verify battery voltage and good chassis and engine grounds; check at ABS module pins under load
Use a capable scan tool to monitor raw CAN messages from Brake System Control Module A and related messages
Perform wiggle test on harness while monitoring network for intermittent errors (vehicle secure and parked)

CAN message types: wheel speed, brake pressure, ABS status, slip flags (typically periodic broadcast messages)
Typical update rate: wheel speed and ABS event messages: 10–100 Hz (varies by manufacturer)
Expected value ranges: wheel speed 0–300 km/h (or 0–188 mph), brake pressure within sensor-specific range; flags should be boolean/bit fields
Message integrity: correct CAN ID, DLC (data length), and checksum/CRC where used
Look for malformed frames (incorrect DLC), frequent error frames, or repeated single CAN ID corruption

Connect OEM-level scan tool and read all modules; note all communication-related DTCs and freeze frame data
Check vehicle battery state-of-charge and charging system; ensure battery above minimum operating voltage for diagnostics
Visually inspect ABS module connector and wiring; repair any corrosion, bent pins or damaged insulation
With ignition ON and scan tool connected, monitor raw CAN messages from Brake System Control Module A and adjacent modules; note missing, malformed, or inconsistent messages
If messages are missing or corrupted, isolate: check CAN continuity, resistance between CAN High and Low, and to ground; look for shorts to battery/ground
Perform wiggle test of harness and connectors while monitoring network for changes to replicate intermittent faults
If wiring and power/ground are good but invalid data persists, try reflashing or updating module software to correct calibration mismatch (follow OEM procedures)
If reflashing fails and diagnostics point to the module, consider replacement of Brake System Control Module A and follow manufacturer programming/initialization procedures
After repairs clear codes and perform a controlled road test verifying ABS, traction control, and that the U0418 code does not return; re-check for related codes

Intermittent CAN bus open/short, high resistance, or loose connector at brake module
Low battery voltage or poor ground at the ABS module during communication
Failed ABS module network transceiver or internal memory corruption
Aftermarket device or recent module replacement with incompatible software/calibration
Corroded pins or water ingress in ABS connector causing bit errors