The electronic control unit ECU 05B906005 with Bosch hardware 0281015165 is one of the commonly used controllers in Audi models. It manages the injection system, CAN bus communication, mixing and a number of engine protection functions.
Under certain conditions, errors may occur that impede vehicle operation or result in a complete lack of communication with the module.
This article looks at the most common problems: P1040, P1042 and a situation where after a software update the vehicle cannot establish a connection to the ECU.
Error P1040 - Problem in electrical control of injector "A"
Error P1040 indicates that there is a power or control fault in the first injector. The controller reports that the signal to the injector is not within normal limits.
How it manifests:
uneven engine operation
skip on acceleration
Check Engine light on
reduced power
Possible causes:
problem in the electrical installation
break in the signal line
oxidation or poor contact
incorrect control by ECU
Error P1042 - Problem in electrical control of injector "B"
P1042 is analogous to P1040 but refers to the second injector. The module detects an incorrect voltage or signal in its control circuit.
Symptoms:
idling vibrations
sluggish acceleration
increased fuel consumption
"Check Engine" is on
Reasons:
unstable power supply
broken cable
bad connection in the books
management difficulties on the part of the ECU
No communication with ECU after software update
This is one of the most serious problems where:
the vehicle does not recognise the module
no connection via CAN bus
the diagnostic device cannot establish communication
the vehicle often fails to start or enters emergency mode
What can lead to this:
incomplete or interrupted software recording
voltage drop during the update
blocking communication protocols
the module enters protection mode
incompatible or corrupted software
In such a situation, the ECU almost always needs professional recovery.
What happens if the problem is not solved?
Prolonged driving with such errors can lead to:
unstable engine operation
difficulty in burning
reduced power
increased cost
risk of additional damage
In the absence of communication, the vehicle may completely lose the ability to diagnose and control.
