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What Are Common Reasons My Mercedes Benz Won’t Start?

As with every machine, the Mercedes Benz occasionally fails to perform as intended.

The Mercedes Benz won’t start for a number of reasons, but three of the most frequent are a dead battery, an alternator issue, or a broken starter.

Starting your Benz normally is often hindered by a dead key AGM battery, corrosion on the terminals of the batteries, a clogged fuel filter, an inoperable starter, a blown fuse, an empty gas tank, an immobilizer mistake, or other electrical system faults.

Let us discuss a few common reason why the Mercedes Benz fails to start –

Week battery

A weak or dead battery is most likely to cause your Benz’s engine to crank slowly. If the battery is the cause of the starting difficulty, a closer look and a battery voltage test will reveal the truth. 

The voltage between the battery poles, the acid level, and the condition of the starting battery may all be tested by a battery repair specialist from your local garage.

Battery corrosion

Cable contacts in your car batteries can corrode, causing the battery to lose contact and limit current flow, preventing your engine from starting.

You must inspect your Benz’s battery contacts to see if they are dirty. Check the battery terminals for corrosion by lifting the rubber coverings over the two terminals on the battery. 

As long as there are no fractures or other damage to the battery, you don’t need to replace it. Simply clean it.

Broken starter motor

As the name suggests, a starter is a motor used to start the engine of your Benz. If the engine is started more frequently, the starting motor’s lifespan will be decreased. Due to its limited lifespan, the starting motor will also fail after a lengthy period of use, and if the starter motor fails, the engine won’t start.

You will hear a clicking sound when you turn the key to start the engine in your Mercedes Benz. In addition, if the starter motor does not work with a fully charged battery, consider a starter problem.

It is typically necessary to repair the starter if it malfunctions.

Alternator issue

Electricity is produced by an alternator. A faulty alternator will prevent your Mercedes Benz’s battery from charging. When the battery runs out, even if you assume that the engine won’t start because of a dead one, your car won’t start.

Alternators tend to last for a long time. It is believed that contemporary automobiles will survive between 200,000 and 300,000 miles because of their enhanced performance. 

A second hand car’s alternator, however, may be fairly old and prone to failure depending on how it’s used. Be on your guard. It is necessary to replace the alternator if it causes any sudden issue or is too old.

Fuel pump failure

Benz’s engine will not start if its fuel pump malfunctions. A proper fuel pump guarantees that the engine’s injection system receives enough gasoline from the tank at sufficient pressure.

Before your fuel pump quits operating, it is generally noticeable: if your car’s engine frequently fails to start, jerks, or performs poorly, you should get it examined.

Clogged fuel filter

In contrast to a mechanical element, the gasoline filter in your Mercedes Benz is clogged over time by dirt and airborne particles. The filter’s permeability decreases, and the fuel pressure decreases as well. 

However, if the gasoline filter becomes sufficiently clogged, it can cause the engine to lose performance and, in rare cases, fail to start. The filter can not be cleaned, it can only be changed.

Camshaft position sensor

A camshaft position sensor is included in Mercedes Benz to ensure that they operate smoothly and without timing problems, according to the manufacturer. Unfortunately, this sensor is prone to malfunction and will need to be replaced as a result.

After leaving the car off for a few minutes or hours, the car will start as if nothing was wrong with it and the engine will turn over properly, but it will not start. 

Several times, your automobile starts without a hitch, but then the problem returns without notice. A camshaft position sensor is usually installed on each bank of cylinders in a V-shaped engine; if one fails, you’ll probably need to replace both.

Mass airflow sensor

The mass airflow sensor is used by the car’s engine management computer, as all current Benzs are electronically fuel-injected. Commonly known as a MAF sensor, this device is used to determine how much fuel needs to be pumped into each cylinder for maximum efficiency and performance.

This is because when the MAF sensor fails, the engine management computer receives incorrect information and injects incorrect air-fuel ratio gasoline into   the engine, which prevents the car from starting. Disconnect the wire from the MAF and attempt to start the car. 

The engine management computer will utilize a simple engine map because it does not get any information about the air from the MAF. Your Benz’s MAF may need to be cleaned or changed if the engine starts with the MAF unplugged.

Vacuum System Leak

Mercedes Benz’s suction system and MAF sensor operate together. EGR (exhaust gas recirculation) leaks are most frequent on the Mercedes Benz, although they can occur on other versions as well. 

To recycle unburned engine gases back into the combustion chamber, the EGR system is responsible. These gases are subsequently burnt, resulting in a cleaner-running engine as a result of the process. Due to the fact that the EGR system uses vacuum pipes, these unburned gases might escape.


You should keep in mind that if you have not kept up with your Mercedes Benz’s routine maintenance, the problems may be more severe and require far more expensive repairs, such as an engine rebuild.

Other problems, such as old wiring, broken connections, and poor maintenance, may be to blame.

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