What does fault code ECM-U042E00 mean?

Diagnostic fault code details for ECM-U042E00 (Volvo S60 (2011–), Volvo S80 (2007–), Volvo V40 (2013–)). Repair service at OBD Tuning.

VOLVO

ECM-U042E00 - Invalid Data Received From Generator Control Module. General Failure Information. No sub type information

System

Engine Control Module (ECM)

Volvo models this fault code applies to

Applies to the following models:

8 models

S60 (2011–), S80 (2007–), V40 (2013–), V40 Cross Country (2013–), V60 (2011–), V70 (2008–), XC60 (2009–), XC70 (2008–)

Show models by year and engine (8)

What does this fault code mean?

On request from the central electronic module (CEM) over CAN, the ECM controls the alternator's charge voltage via LIN. The code is set when there is a disturbance in communication with the alternator control module (ACM). The ACM then charges at a fixed voltage instead of regulating the charge.

Possible causes

Internal fault in another control module on the same part of the LIN network
Damaged alternator control module (ACM), which is the charge regulator

What you can do

1Check the battery and its connections, since the fault shows up as a dead or weak battery.
2Look for loose, chafed or corroded connectors at the alternator and on the wiring to it.
3Have a workshop read out the fault codes and troubleshoot the alternator control module and LIN communication with diagnostic equipment, as this requires measurement.

Symptoms you may notice2

Dead battery
Low battery or weak electrical power

What the fault can affect1

The alternator control module (ACM) charges at a fixed voltage

General guidance for car owners. Diagnosis on the car can point to a different cause.