Fault code lookup

NetworkU0129

Serious

Severity: Serious - have it checked soon

Lost Communication With Brake System Control Module

39 brands affected · Generic SAE J2012 description.

Key terms: Control module: a small computer that runs one part of the car · SAE J2012: the standard generic code list

Safety: This code relates to the braking system or brake assist. Braking may be affected.

1What it means in plain English

Control modules in the car cannot communicate with each other over the vehicle network.

2Common causes

  1. Wiring or connector fault on the communication bus
  2. Faulty control module
  3. Low battery voltage or poor ground
  4. Water ingress in a connector or module
  5. Aftermarket device interfering with the bus

3Can I drive?

Serious · drive with care

The car may run normally or may not run at all. If the module that has lost communication controls steering, brakes, park brake, charging or engine cooling, drive only if those systems feel normal; stop safely if the steering becomes heavy, a brake warning appears, or the engine temperature climbs. If the car will not start or runs badly, have it towed.

This page gives general information. It is not professional advice. For a definite diagnosis and a repair quote, ask a qualified mechanic to inspect the car.

4Brand data 39

BrandCodeDescriptionSystem
Ashok Leyland CVU0129Lost Communication With Brake System Control Module SAENetwork
BAIC MotorU0129With ABS/BSM Loss of communication BrandNetwork
Mercedes-BenzU0129Lost Communication With Brake System Control Module SAENetwork
BYDU0129Communication with PM2.5 green clean system lost BrandNetwork
CheryU0129CAN-BSM Signal Timeout BrandNetwork
DaewooU0129Lost Communication With Brake System Control Module BrandNetwork
DaihatsuU0129ABS receiving failed BrandNetwork
DFFSU0129Lost communication with BAE CAN BrandNetwork
DFFXU0129Lost Communication With Brake System Control Module BrandNetwork
DFXKU0129Lost Communication With Brake System Control Module BrandNetwork
EOBDU0129Tabt kommunikation med bremsestyringsmodul 'A' BrandNetwork
FordU0129Lost Communication With Brake System Control Module SAENetwork
GeelyU0129Lost Communication With Brake System Control Module BrandNetwork
GMU0129Lost Communication With Brake System Control Module BrandNetwork
Great WallU0129Lost Communication With Brake System Control Module BrandNetwork
HafeiU0129Lost Communication With Brake System Control Module BrandNetwork
HoldenU0129Lost Communication with Brake System Control Module BrandNetwork
HondaU0129Electric servo brake control unit communication error (radar vision unit). Fault location and estimated cause: Electric servo brake control unit fault BrandNetwork
HyundaiU0129Lost Communication With Brake System Control Module SAENetwork
IsuzuU0129Lost Communication With Brake System Control Module SAENetwork
Land RoverU0129Lost Communication With Brake System Control Module SAENetwork
MaseratiU0129Lost communication with Brake System Module (BSM) 1 BrandNetwork
MazdaU0129Lost Communication With Brake System Control Module SAENetwork
MitsubishiU0129Lost Communication With Brake System Control Module SAENetwork
NissanU0129Lost Communication With Brake System Control Module SAENetwork
OpelU0129Lost Communication With Brake System Control Module BrandNetwork
PeroduaU0129ABS receiving failed BrandNetwork
PeugeotU0129Lost Communication With Brake System Control Module SAENetwork
PorscheU0129Lost Communication With Brake System Control Module SAENetwork
ProtonU0129Lost Communication With Brake System Control Module SAENetwork
SaabU0129Lost Communication With Brake System Control Module BrandNetwork
Maxus (SAIC)U0129Lost Communication With PLG BrandNetwork
MG (SAIC)U0129No SIM Challenge received BrandNetwork
SmartU0129Lost Communication With Brake System Control Module SAENetwork
SubaruU0129Lost Communication With Brake System Control Module SAENetwork
SuzukiU0129Lost Communication With Brake System Control Module SAENetwork
TataU0129Lost Communication With Brake System Control Module BrandNetwork
ToyotaU0129Lost communication with Adaptive Cruise Control (ACC) BrandNetwork
VolkswagenU0129SAE: No Communications with Brake System Control Module BrandNetwork

Legend: SAE is the generic J2012 description; Brand is text taken from that manufacturer’s data. Manufacturer rows keep the wording and language of the source data, and non-English text is tagged so screen readers pronounce it correctly.

5Extended variant codes 3

These 7-character codes are manufacturer-specific variants of U0129 and may be reported by some scan tools.

BrandCodeDescriptionSystem
SsangYongU012900CAN communication: Electronic Stability Control (ESC) message not received BrandNetwork
Mercedes-BenzU012908Die Kommunikation mit dem Steuergeraet 'Rekuperatives Bremssystem' hat Funktionsstoerung. Es liegt ein Signalfehler vor oder die Botschaft ist fehlerhaft. BrandNetwork
SsangYongU012986CAN communication: Anti-lock Brake System (ABS)/Electronic Stability Program (ESP) message not received (G-sensor) BrandNetwork

6Related codes

  • U0120 Lost Communication With Starter / Generator Control Module
  • U0121 Lost Communication With Anti-Lock Brake System (ABS) Control Module
  • U0122 Lost Communication With Vehicle Dynamics Control Module
  • U0123 Lost Communication With Yaw Rate Sensor Module
  • U0124 Lost Communication With Lateral Acceleration Sensor Module
  • U0125 Lost Communication With Multi-Axis Acceleration Sensor Module
  • U0126 Lost Communication With Steering Angle Sensor Module
  • U0127 Lost Communication With Tire Pressure Monitor Module
  • U0128 Lost Communication With Park Brake Control Module
  • U012A Lost Communication With Chassis Control Module A
  • U012B Lost Communication With Chassis Control Module B
  • U012C Lost communication with active vibration control module

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