NetworkU012D

Serious

Severity: Serious - have it checked soon

Lost Communication With Generator A Control Module

19 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 charging system. The battery may go flat and the car may stall.

1What it means in plain English

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

2Common causes

Wiring or connector fault on the communication bus
Faulty control module
Low battery voltage or poor ground
Water ingress in a connector or module
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 19

Brand	Code	Description	System
Ashok Leyland CV	U012D	Lost Communication With Generator A Control Module SAE	Network
BAIC Motor	U012D	Lost Communication With Generator Control Module Brand	Network
Daewoo	U012D	Lost Communication With Generator A Control Module SAE	Network
DFFS	U012D	Lost communication with generator Brand	Network
DFFX	U012D	loses communication with generator control module Brand	Network
DFXK	U012D	Communication between ECU and smart generator lost Brand	Network
EOBD	U012D	Kaotatud side generaatori 'A' juhtmoduliga Brand	Network
GM	U012D	Lost Communication With Generator A Control Module SAE	Network
Holden	U012D	Lost Communication With Generator A Control Module SAE	Network
Honda	U012D	Lost Communication With Generator A Control Module SAE	Network
Hyundai	U012D	Lost Communication With Generator A Control Module SAE	Network
Isuzu	U012D	Lost Communication With Generator A Control Module SAE	Network
Land Rover	U012D	Lost communication with generator control module Brand	Network
Maserati	U012D	Lost communication with alternator control module Brand	Network
Opel	U012D	Lost Communication With Generator A Control Module SAE	Network
Peugeot	U012D	Lost Communication With Generator A Control Module SAE	Network
Proton	U012D	Lost Communication With Generator A Control Module SAE	Network
Saab	U012D	Lost Communication With Generator A Control Module SAE	Network
Toyota	U012D	Communication between ECM and generator control module LIN (C12D) lost Brand	Network

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 1

These 7-character codes are manufacturer-specific variants of U012D and may be reported by some scan tools.

Brand	Code	Description	System
Hyundai	U012D00	If LIN message from alternator is not received, ECM sets DTC Brand	Network

6Related codes

Browse Uxxx codes or U012xx codes.