The engine computer is an essential part to ensure the electronic functioning of the various sensors and actuators present within your vehicle. In this article, we present to you the different functionalities of the engine computer, how it works and how to unlock it.

Table of contents

What is the engine computer?

The engine computer manages and controls the electronic functions of the engine. It is made up of the ECU (Engine Control Unit), a waterproof metal housing designed to withstand different weather conditions. This waterproof coating also helps protect the interior of the case, which mainly contains electronic compounds.

The engine computer is divided into 3 parts : reception of incoming signals, processing of various data and sending of outgoing signals. It contains sensors and actuators to electronically manage the general operation of the engine in several aspects:

  • Engine ignition ;
  • Engine injection ;
  • The transmission of information ;
  • Vehicle safety ;
  • The comfort of the car .

How does an engine computer work?

The engine computer transforms the mechanical actions of your vehicle into electronic signals to inform you in the event of a problem. If a light comes on on your dashboard, it is thanks to the engine computer which has translated the manifestation of a mechanical problem into an electronic signal. This translation of information is done via actuators, parts connected to the engine computer.

In order to understand the difference in function between sensors and actuators, here are some representative examples:

For actuators

  • The spark plugs, present in the combustion chamber , ignite the air and fuel mixture for gasoline engines;
  • The injectors send fuel either into the engine’s air intake duct or into the cylinder.
  • The EGR valve (Exhaust Gas Recirculation in English) which reduces toxic gas emissions by reinjecting recycled exhaust gases into the engine.
  • The throttle body adjusts the quantity of air required by the engine depending on the power.

For the sensors

  • The accelerator pedal sensor allows the engine to vary the vehicle speed depending on the position of the pedal.
  • The temperature sensors indicate the temperature of the elements constituting the engine .
  • The camshaft sensor sends signals relating to the engine’s combustion cycle.
  • The knock sensor signals abnormal combustion in the engine.
  • Lambda sensors measure the quality of the vehicle’s exhaust gases .

What are the symptoms of a broken engine computer?

When your engine computer is broken, this can manifest itself in several situations:

  • It is impossible to start your vehicle;
  • The operation of the engine speed is slow;
  • Fuel consumption increases exponentially;
  • ABS or ESP no longer work correctly;
  • On the dashboard, several lights are on at the same time;
  • A lack of engine power is felt;
  • The vehicle is unstable when accelerating.

What to do when the engine computer is out of order?

Depending on the problem that the engine computer encounters, several solutions may be available to you. In fact, in certain cases, repairing the Engine Service Box ( BSM ) may be enough to resolve the malfunction. You will have to dismantle the engine computer to carry out the intervention.

If, on the other hand, it is a fault that cannot be solved by a simple repair, you will have to change your BSM . Thus a reprogramming will be carried out. For this you can contact the manufacturer.

How to unlock an engine computer?

In some cases, the engine computer can lock up and prevent your car from starting. In order to unlock it, follow our step-by-step guide.

Necessary material :

  • A toolbox
  • Gloves and protective glasses

Step 1: Check the general condition of the computer

Start by checking that there has been no water infiltration or short circuits within the computer.

Step 2: Check the computer connections

Here you will have to check the power supplies, masses, continuity and insulation lines between the BSM (Engine Service Box) and the engine computer. Reconnect areas where power supplies may be disconnected.

Step 3: Carry out a test

Try to start your vehicle by placing a weight directly on the body of the engine computer.

How much does an engine computer repair cost?

A computer failure is uncommon, it often concerns the peripherals connected to it such as actuators, sensors or even electrical harnesses. For example, the electrical harnesses can be damaged or even cut due to vibrations coming from the engine.

If your ECU is broken, you can opt for a standard ECU exchange . It is often much cheaper than a new model but must be programmed to match your vehicle.

If your computer can be repaired or reprogrammed, the repair costs around €150. However, if your computer needs to be changed, the price of this part varies between 200 and 600 euros depending on the model, to which the cost of labor must be added.

The engine computer is a key element in informing you about the condition, safety and comfort of your vehicle. This is why it must be maintained well and entrusted to trusted mechanics in the event of a breakdown. To obtain a precise quote for your engine computer repair, our garage comparator is there to support you in your efforts.

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