NetworkU1121

Serious

Severity: Serious - have it checked soon

Communication failure with electric steering ECU

29 brands affected · Description from Toyota data.

Key terms: Control module: a small computer that runs one part of the car

Safety: This code relates to the steering system. Steering effort may increase.

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 29

Brand	Code	Description	System
Mercedes-Benz	U1121	No description available	Network
BYD	U1121	No description available	Network
Chery	U1121	No description available	Network
Daewoo	U1121	Loss of serial communications for class 2 devices Brand	Network
Daihatsu	U1121	Lost communication with driver monitor ECU Brand	Network
DFFS	U1121	ESC related message lost Brand	Network
DFFX	U1121	No description available	Network
EOBD	U1121	CAN Antar-sistem Brand	Network
Geely	U1121	No description available	Network
GM	U1121	Loss of serial communications for class 2 devices Brand	Network
Great Wall	U1121	No description available	Network
Hafei	U1121	No description available	Network
Holden	U1121	Lost Communication with Power Steering Control Module Brand	Network
Hyundai	U1121	No description available	Network
Isuzu	U1121	No description available	Network
Maserati	U1121	Lost Communication With LIN ECU 1 Brand	Network
Mitsubishi	U1121	EPS CAN timeout Brand	Network
Opel	U1121	Loss of serial communications for class 2 devices Brand	Network
Perodua	U1121	Lost communication with driver monitor ECU Brand	Network
Peugeot	U1121	No description available	Network
Proton	U1121	EPS CAN timeout Brand	Network
Saab	U1121	Loss of serial communications for class 2 devices Brand	Network
MG (SAIC)	U1121	Lost Communication With BMS Module on CAN1 Brand	Network
Smart	U1121	No description available	Network
Sprinter	U1121	No description available	Network
Suzuki	U1121	Lost Communication With ABS / ESPControl Module Brand	Network
Tata	U1121	Message Time-Out With ABS/ESP Brand	Network
Toyota	U1121	Communication failure with electric steering ECU Brand	Network
Volkswagen	U1121	Databus: missing message 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 U1121 and may be reported by some scan tools.

Brand	Code	Description	System
Porsche	U112100	Displaycode Brand	Network
Volkswagen	U112100	data bus, missing message Brand	Network

6Related codes

Browse Uxxx codes or U112xx codes.