Mercedes-Benz Won’t Start | Step by Step Troubleshooting Guide

A common problem in automobile life is that the car does not start. Here's a list of common places to look check on a Mercedes-Benz.

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Are you having the problem that your Mercedes won’t start? Do you experience no start issues for Mercedes-Benz? Engine turns on and the car won’t start? Perhaps it starts again a second later but dies. This is a standard car starting problem for many models of cars. These steps should give you the most accurate advice in dealing with Mercedes-Benz no-start problems. Although troubleshooting can be done on your own, sometimes, it is possible that you might need to replace the battery or that there could be another error that needs to be checked. 

To find out more, read our in-depth guide:

My Mercedes Won’t Start Troubleshooting Guide

A common problem in automobile life is that the car does not start. It is often necessary to go to a shop, but it is possible to carry out various tests yourself and determine the problem. Here’s a list of commonplaces to look check on a Mercedes-Benz.

Verify That Battery Is Fully Charged

This seems obvious, but old batteries cause many headaches and can cause various mechanical issues in some Mercedes cars. How old are the batteries of Mercedes-Benz? Although some users have used their batteries for many years, the factory battery can at some point let you down. It can now be upgraded to a new aftermarket battery that will last 6 or 7 years. If you’re having trouble, starting your car and you are still using old batteries, then you should replace them. The new battery will cost you a few pounds, and it can also help with your starting problems. Our batteries are less costly than those purchased at dealer stores, while still exceeding quality standards for German vehicles.

We offer high-quality Mercedes-Benz Banner batteries suited for your needs.

Check Gear Selector / Brake Light Switch

Brake lights are a common issue that often fails in Mercedes-Benz vehicles. This means the vehicle cannot start unless the brake lights are not working correctly. Sometimes there will be problems with parking the car. They equipped the brake light switch with two micro-switches inside that regulate the brake lights. Replacing these is an easy fix that can be done DIY or by a mechanic.

Transmission problems have also caused non-start situations in many models from Mercedes Benz. There might be a fault with the gear selector which could prevent the car from going into neutral, which is necessary for the car to start. 

Check Crankshaft position sensor – Crank No Start

When the crankshaft is damaged or faulty, there may be a crank turn over but no start symptoms. When the motor crank position sensors fail, you will see the following symptom: The Mercedes-Benz engine is turning but won’t start because of the failure of its crank position sensor. Replacing the crank position sensor is simple and fairly inexpensive.

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Mechanic checking car fuses

Check fuses and relays

Mercedes won’t start, and there are no batteries? You’ll need to check the vehicle fuses. Check the fuses for these certain parts, which are important: starter, ignition, engine ignition, and pump. It may vary from model to model whether a certain circuit affects starting. If you’re uncertain about the layout of the fuses, you’ll need to check your fuse box to see the location and then determine if there is any burnout. Remember that the fuse should prevent a system from malfunctioning. Replace the fuse with a similar fuse with the same Amp rating.

Systems to check to troubleshoot a Mercedes-Benz Starting Issue

Other limitations may include ECM / PCM computer failures, electrical problems, faulty camshaft position detection devices, or the driver’s authorisation device/immobiliser device.

Mercedes won’t start – Fuel Problems

Does the motor turn on and do the electrics work? Then the issue might be fuel related. Troubleshooting fuel-related issues can be done easily. The fuel level can easily be measured. This test requires fuel pressure gauges. It is necessary for your fuel pressure gauge to have a Schrader valve adapter for Mercedes-Benz. 

Ignition System, Spark plugs/Coils – Mercedes starts then dies

The second reason the vehicle won’t start is because of the spark plugs and/or coils. This is a pretty common problem. If you have spark and your fuel pump works well, then it’s the ignition system. If you have a multimeter. Then check the voltage at the coil (remembering that it’s negative ground) with the key on and cranking. You should have around 20 volts. If it’s less than 10 volts, replace the coil. Always check that the plug wires are tight before replacing a coil. If you don’t have any spark, then it’s time to change plugs and coils or get them checked at a shop.

The spark plugs on your car can be a little confusing to check, but it’s an important part of being a good car owner. If you aren’t sure how to do this yourself, take your car to a mechanic or even to a parts store and they can help you with this step.

Trouble Shooting The Sparkplugs 

If your engine is misfiring or not starting at all, the problem could be your spark plugs. It’s important to have these replaced if you think they are bad, so you can get back on the road safely.

How to Check Your Spark Plugs

Checking your mercedes-benz spark plugs

To check your spark plugs, look at the gap between the ground electrode and the centre electrode. This gap should be 0.040 inches wide for every plug. If they are less than this, replace them. The electrodes should be covered in black soot, but if they’re white or clean, you will need to replace them as well. Spark plugs need replacing every 30 000 kilometres or 24 000 miles, whichever comes first.

Starter Motor Problems – Mercedes won’t turn over

If a starter is defective, there’s no chance of turning the motor. Often a damaged starter will explode a fuse that protects the starter. Based on your starter problem, the starter may still work several times. Even when the starter starts, consider replacing it. 

Electronic Key Ignition System

The car may not be operating because of a driver authorisation system failure. The newer keys feature transponders. Remote keys have both a transponder and battery. Replacing the battery in the key will help to solve this issue.

Other Possible Problems – Mercedes won’t start not battery

There are many reasons why your Mercedes-Benz won’t start. If you checked the above you are doing well. This last step requires an advanced diagnosis to be performed. The recommended scanner is the Autel D7008 – Professional Scanner which works with all types of cars. When you plug the OBD-II scanner into the OBD-II port of the car you will be able to scan several components for the cause of the problem. 

Check Engine Fault Codes

When a Mercedes-Benz starts to have problems it will show various fault codes. There are many ways to find out the correct fault codes. The iCarsoft MB2 or Launchcreader XI+ are both easy devices to help retrieve fault codes. They can also extract fault codes for TUC, SRS, ESP, ETS, AAS, and other control devices in a single scan. 

Top Mercedes Won’t Start Problems

Fuel Pump

The fuel pump is an electrical component that has the function of supplying automotive engines with pressurised fuel. This component is one of the most vital parts in your car, as it not only helps to start the car but provides the engine with fuel.

The fuel pump is an integral part of the fuel injection system of the car. The latter handles the supply of adequate amounts of fuel to all cylinders of your engine, which will allow it to run properly and efficiently.

If there are some problems with this component, then you can experience a multitude of issues with your car’s performance: the engine sputters, it may start running unevenly, or maybe it even refuses to start altogether. The problem may occur, regardless of weather or the time your car has been used for.

We hope that you found this blog helpful and that we were able to give you some solid car advice. If you have any more questions feel free to reach out and remember to keep an eye on our blog page as we post new blogs regularly.

Embracing the Shift to Electric – Troubleshooting for Electric and Hybrid Mercedes-Benz

White Mercedes Benz EQC

As of 2023, Mercedes-Benz has been making a significant push into electric and hybrid vehicles. Understanding the new set of challenges that come with electric vehicles (EVs) and hybrid electric vehicles (HEVs) is essential for Mercedes owners who want to troubleshoot starting problems. Here’s what you need to know:

Battery Management System (BMS) in Electric and Hybrid Models

Mercedes electric and hybrid vehicles are equipped with sophisticated Battery Management Systems. If your EV or hybrid is not starting, it could be due to an issue with the BMS. This system ensures the battery operates within safe parameters, so if it detects an issue, it might prevent the vehicle from starting to avoid damage.

Electric Drive Unit Issues

Electric and hybrid Mercedes models rely on an electric drive unit instead of a traditional internal combustion engine. If your electric Mercedes isn’t starting, the issue could be with the electric drive unit. This might be due to a software glitch or a physical problem with the unit. In such cases, it is best to consult a specialist or take your vehicle to a certified Mercedes-Benz service center.

High Voltage Battery

Just like traditional vehicles have a 12-volt battery, electric and hybrid vehicles have high-voltage batteries. If your electric or hybrid Mercedes isn’t starting, it’s essential to check the state of charge of the high-voltage battery. In electric vehicles, this battery is critical for starting and driving the car.

Electric Charging Infrastructure and Fast Charging

As electric vehicles become more common, Mercedes-Benz has been incorporating fast charging capabilities in their vehicles. If you are using a fast charger, make sure it is compatible with your vehicle. Sometimes, incompatible charging equipment can cause issues with the car’s battery and result in starting problems.

Updates on Recall Information

Mercedes-Benz, like other car manufacturers, occasionally issues recalls for certain car models if a defect is identified. It’s important to stay updated with the latest recall information and ensure that your vehicle is not affected. If there is a recall, it is advisable to follow the manufacturer’s instructions and take your car to an authorized dealer for inspection and repair.

Frequently Asked Questions (FAQs)

My Mercedes won’t start. What could be the problem?

There could be various reasons why your Mercedes isn’t starting. It might be due to an old or depleted battery, issues with the gear selector or brake light switch, a faulty crankshaft position sensor, problems with fuses and relays, or issues with the ignition system and spark plugs. Additionally, fuel problems, starter motor issues, and electronic key ignition system failures can also be causes. For electric or hybrid models, the Battery Management System or Electric Drive Unit might be affecting startup.

How can I tell if my Mercedes’ battery needs to be replaced?

If your Mercedes is having trouble starting and is using an old battery, it might be time to replace it. Old batteries can cause various mechanical issues. If your battery is several years old and you’re experiencing starting problems, consider upgrading to a new aftermarket battery that meets quality standards for German vehicles.

What should I check if my Mercedes’ engine turns but the car won’t start?

If the engine cranks but doesn’t start, it could be due to a faulty crankshaft position sensor. When this sensor fails, the engine turns but won’t start. Replacing the crankshaft position sensor is simple and fairly inexpensive. Additionally, check the fuel system and the ignition system, as the problem could be fuel-related or due to spark plugs and/or coils.

How do I troubleshoot spark plug issues in my Mercedes?

To troubleshoot spark plug issues, first, check the gap between the ground electrode and the center electrode. It should be 0.040 inches wide for every plug. If they are less than this or if the electrodes are clean instead of covered in black soot, you should replace them. Spark plugs should generally be replaced every 30,000 kilometers or 24,000 miles.

What should I do if my electric or hybrid Mercedes won’t start?

For electric and hybrid Mercedes models, the Battery Management System (BMS) or Electric Drive Unit might be causing startup issues. If your electric or hybrid Mercedes is not starting, it’s advisable to check for issues with the BMS, which ensures the battery operates within safe parameters. If the BMS detects an issue, it might prevent the vehicle from starting to avoid damage. Additionally, check the Electric Drive Unit as issues with this unit could also prevent your electric Mercedes from starting.

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