NetworkU0077

Serious

Severity: Serious - have it checked soon

Control Module Communication Bus E Off

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

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	U0077	Control Module Communication Bus E Off SAE	Network
BAIC Motor	U0077	EMS_ID118 exception: lost or timeout Brand	Network
Mercedes-Benz	U0077	Control Module Communication Bus E Off SAE	Network
Chery	U0077	Cell monitor unit BusOff Brand	Network
Daewoo	U0077	Control Module Communication Bus E Off SAE	Network
EOBD	U0077	Juhtmoduli sidebuss 'E' väljas Brand	Network
Geely	U0077	CAN message ACU check and fault Brand	Network
GM	U0077	Control Module Communication Bus E Off SAE	Network
Holden	U0077	Control Module Communication Chassis Expansion CAN Bus Off Brand	Network
Land Rover	U0077	Control Module Communication Bus E Off SAE	Network
Mitsubishi	U0077	Control Module Communication Bus E Off SAE	Network
Opel	U0077	Control Module Communication Bus E Off SAE	Network
Peugeot	U0077	Control Module Communication Bus E Off SAE	Network
Saab	U0077	Control Module Communication Bus E Off SAE	Network
Maxus (SAIC)	U0077	Diagnostic bus off Brand	Network
MG (SAIC)	U0077	Diagnostic bus off Brand	Network
Subaru	U0077	Control Module Communication Bus E Off SAE	Network
Suzuki	U0077	Control Module Communication Bus E Off SAE	Network
Toyota	U0077	Control module communication bus 'E' off 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 2

These 7-character codes are manufacturer-specific variants of U0077 and may be reported by some scan tools.

Brand	Code	Description	System
Volvo	U007700	No description available	Network
Mercedes-Benz	U007788	Control Module Communication Bus 'E' Off. Bus OFF. Brand	Network

6Related codes

Browse Uxxx codes or U007xx codes.