How to Diagnose a Faulty Start-Stop System in Your Volkswagen

Have you observed that your Volkswagen’s start-stop system is not functioning as it should? Ever been in a traffic light waiting to switch off the engine and then rev it to start again only to find it will not engage? Volkswagen’s start-stop system is intended to save fuel by turning off the car’s engine while idle and turning it on when the accelerator pedal is pressed. However, like any other system, it can encounter some challenges from time to time.

If you are among the Volkswagen car owners who experience problems with the start-stop function of their car, you are not alone. This is a common problem that many drivers face, and various reasons can cause it. Here are the most common causes of start-stop system failure and what steps can be taken to rectify the problem.

How Volkswagen’s Start-Stop System Works

The start-stop system works with the help of some sensors, the battery, the alternator, and the engine control unit (ECU) to decide when to turn off and turn on the engine. When you come to a stop, the engine is turned off to conserve fuel. The engine starts immediately without lag whenever the brake is released or the clutch is pressed. However, if the system’s components are faulty, the start-stop function will not operate as required.

Common Causes of Start-Stop System Failure

• Battery Failure: A weak or failing battery is one of the common causes of start-stop system failure. The system depends on the battery to crank the engine fast, and if the battery power is low, the start-stop feature could be deactivated. Volkswagen cars with start-stop technology need an Absorbent Glass Mat (AGM) or an Enhanced Flooded Battery (EFB) since they are suitable for frequent starting.
• Faulty Alternator: If the alternator is not functioning correctly, the battery will not get charged, resulting in start-stop system failure. A bad alternator might also cause headlights to dim, warning lights or indicators on the dashboard to dim, or difficulty starting the vehicle. If you think you have a problem with the alternator, it is advised to seek a mechanic’s help.
• Start-Stop Sensors: Volkswagen’s start-stop system requires several sensors to determine when the engine needs to shut down and restart. These are voltage sensors for the battery, temperature sensors for the engine, brake pedal position sensors, and electrical load sensors. If any of the sensors mentioned above or any other sensor fails or gives wrong signals, the system may not function efficiently.
• ECU issues: The ECU is the main computer of a Volkswagen and oversees various operations, including the start-stop system. If something goes wrong with the software or the programming of the ECU, the system may not turn on.
• Severe Weather: Severe cold or hot temperatures can impact the effectiveness of the start-stop system. The system may be turned off at very low temperatures to protect the battery from being drained. Likewise, the system may not work in very hot conditions if the air conditioning is at its optimal operation. If your start-stop system only fails at extreme temperatures, then it might be a normal function aimed at protecting your vehicle’s electrical system.

How to Troubleshoot Start-Stop System

First, you must find out what is wrong if you have a problem with your Volkswagen start-stop system. Begin with checking the battery status and make sure that the battery has enough power to carry out the task. If the battery is bad or dead, replacing it with a fresh battery can solve the problem. Next, check the alternator, wires, and sensors, as they may cause the problem. If they are not in good shape, then replace them. At other times, software updates or ECU resets may be necessary to correct problems in the system. If all of the above procedures do not work, then it is advisable to seek the service of a professional mechanic.

Franklin Automotive is Your Center For Volkswagen Repairs In Birmingham

If you are dealing with issues concerning the start-stop system in your Volkswagen, then Franklin Automotive is here for you. We can detect and fix problems concerning your battery, alternator, sensors, and ECU to improve your car’s performance. Our workshop is in Birmingham, AL; however, we also cater to drivers from Vestavia, Mountain Brook, Pelham, Hoover, Homewood, and Trussville, AL. Call us to set an appointment for a professional inspection of your Volkswagen vehicle and have it running like new again.