How to know if Your Powertrain Control Module is failing in your Mercedes

Posted on January 17, 2018 by in Auto

A common question that technicians are asked is how to tell if the car computer on the customer’s Mercedes is failing.  Usually the questions are asked due to various symptoms occurring.  The vehicle’s computer, commonly known as the powertrain control module (PCM) is one of the most important components that exist on modern vehicles.  The Mercedes PCM, which is also known as the engine control unit (ECU) or the engine control module (PCM), functions as the main computer.  A problem with the PCM can mean that there will possibly be some sort of serious problems with the automobile.  Although Mercedes vehicles are excellent in quality and performance, problems still can occur, so we will go through the list of common symptoms.

Vehicle Does Not Start

There can be a number of causes for an engine not starting, including a low battery or a bad starter unit, however another reason includes a problem with the PCM.  The PCM will no longer have engine management control if the unit fails completely.  This also includes the vehicle not being able to start up.  The engine may still attempt to start, but it will be unable to get the vital inputs from the PCM.  That is why many people sometimes incorrectly assume that it is the starter that is the cause of the problem.

The Check Engine Light

One of the key symptoms of a PCM going bad on a Mercedes is that the Check Engine Light comes on.  Although the Check Engine Light can mean many things in itself, it is often the first indication of a computer problem.  The first thing to do when the Check Engine Light comes on is to scan the computer for trouble codes, which can reveal if there is an issue with the PCM, or somewhere else on the vehicle.  The first thing to do is to take the car or truck to a qualified technician, unless you happen to know how to properly diagnose and fix the problem.

Engine Misfiring or Stalling

On rare occasion, the engine management controls stops functioning within the PCM.  The faulty computer will cause the car to begin to misfire or stall.  This greatly affects the vehicle’s performance.  The symptoms may happen occasionally as the car is driven, rather than all the time.

Engine Performance Problems

A Mercedes is known for being high quality and performing very well.  However, sometimes the component that is controlling engine firings and timing is having a problem.  A problematic PCM will often impact the engine performance.  This can include a reduction in power and fuel efficiency.

As you know, the engine control module plays an important role with the vehicle and any issues with the PCM can cause major problems.  These computers are highly sophisticated as vehicles become more reliant on them for optimal performance; the more sensitive the car is to computer problems.  When it does fail you can order a high-quality replacement online for a very affordable price.

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