Mercedes Has Power but Won’t Start: Causes and Fixes

Mercedes has power but won’t start due to various reasons. If it does not start, but you hear a clicking sound, you might have a dead battery, corroded battery terminals, or electrical issues.

Other reasons include a damaged starter or faults in the fuel delivery system. Read on to find all causes, symptoms, and learn how to repair a car that has power but does not start.

Why Won’t Your Mercedes Start Even When It Has Power?

Your Mercedes won’t start even when it has power because of a dead or damaged battery. Another common reason is a problem with the starter or ignition switch or a blown fuse. Moreover, fuel system defects or restraint system failures can prevent your Mercedes from starting.

• Corroded or Damaged Mercedes Battery

You should check the battery if your Mercedes won’t start just clicks. The battery may be failing or damaged, so although you will hear the sound, the battery will fail to start the car.
The battery may fail due to loose or corroded terminals, faulty alternators, or if you leave the headlights on. After turning off the accessories, you can test your car’s battery with a multimeter.

First, start the engine and leave it at idle for five minutes. Turn off the engine and remove the negative terminal from your battery. Connect the multimeter probes to the battery and note the voltage. The reading should be around 12 volts. You have a discharged or dead battery if it shows a reading below 12.

While you check the voltage, you should also inspect how the battery is mounted. Make sure it is not knocked or loose. Also, check the cables and terminals. Ensure the cable clamps are tight and hold the wires against the terminals. The battery may fail if you see signs of corrosion or buildup near the terminals.

• Problem With Your Mercedes Starter

The starter is a vital part of a vehicle’s electrical system that initiates the engine’s operation. It is an electric motor connected to the vehicle’s engine, and its function is to turn the engine over so that it starts running on its own.

When you turn the ignition control, the solenoid receives a signal. This signal or electrical current from the car’s battery bridges the starter motor and the battery. When the motor spins or engages with the flywheel, it rotates the engine. This rotation produces the required movement for the engine’s internal elements.

So if the Mercedes won t start but battery is good, you can suspect the starter. In this case, you will not hear a clicking sound, and the engine will not start. You can detect a problem with the starter by switching on the headlights. When you start the engine, you can confirm a damaged starter if they get dim.

Some electrical issues may impact the starter’s performance. These include a flawed ignition switch, damaged wiring, or corroded connections. Such issues prevent the starter from receiving the required current, leading to inadequate power.

Moreover, the starter generates heat while functioning, but excessive heat can harm its components. This problem arises due to a malfunctioning cooling system. Additionally, the internal components of the starter, such as the solenoid or motor, get stuck due to dirt or lack of lubrication. It prevents proper operation and causes damage to the starter.

• Blown Fuse in Your Mercedes

When you start the Mercedes turn key, nothing happens if you have a burnt fuse. Like your home, your Mercedes has many fuses that protect different circuits and accessories. These fuses save the day in case there is an enormous electric surge. The fuses blow up and cut the electric flow across the circuit with issues. So if electric fluctuations occur and the fuse blows in the circuit linked to the engine, your Mercedes won’t start.

Other accessories, such as lights, will keep working in this case. You can confirm the fuse problem by finding the fuse box. Open the box and inspect the fuses.

If you find a burnt fuse, disconnected wires, or damaged connections, you will have the culprit. While checking the fuses related to the engine, starter, or ignition, you should also observe the others.

• Ignition Switch Troubles in the Mercedes

The ignition switch is an electrical component repeatedly used whenever you start or stop the engine. With time, the electrical contacts in the button can wear out, causing poor connectivity or failure. Moreover, exposure to moisture, harsh temperatures, or corrosive substances can damage the switch and its connections. Moisture ingress or corrosion disrupts the electrical flow, resulting in a switch failure.

Sometimes the switch gets damaged due to a faulty ignition cylinder, the part where you insert the key. A worn ignition cylinder prevents the button from receiving the necessary signal when you turn the key. A worn switch causes difficulty in starting the engine. Either nothing happens when you turn the key, or the Mercedes C230 – cranks but wont start.

The problem will also affect various accessories in the vehicle. For instance, you may experience issues with headlights, radio, interior lights, or power windows. Additionally, you may face difficulty removing the key after shutting off the engine. This can occur because the switch fails to recognize the proper position to free the key.

• Fuel System Defects Preventing Car From Starting

If you have ruled out the above mentioned causes, your car might have a fuel system problem. The system comprises many components, and any parts can get damaged, preventing fuel supply to the engine. As a result, the Mercedes does not start.

These issues cause the headlights to dim when people start the engine, so that is a way to test it. Moreover, although it may sound stupid, you may still need to fill the gas, which can be why your Mercedes does not start.

If that’s not the case, there are other possibilities. Your car’s fuel line might have frozen, preventing the engine from cranking. It happens in cold areas where the temperature drops beyond freezing. It also explains why the Mercedes won’t start in cold weather. Even if it does not freeze, the fuel may get thicker. You can wait for the fuel to thaw or use a fuel additive that prevents fuel from freezing.

If the fuel gauge gets damaged, it will show incorrect gas levels in your car. So even when the fuel tank is dry, the needle will tick up. Similarly, the fuel level sensor can get damaged and show false readings.

The fuel filters can also get clogged due to dirt or debris. As a result, the filter prevents the fuel from flowing into the engine. Other fuel system components, such as the fuel pump relay or fuel injectors, can also clog or get damaged.

Sometimes a spark plug or the ignition coils fail to produce the spark required to crank the engine. Although, rarely, all plugs fail simultaneously, it is still possible. Additionally, the car crankshaft position sensor can malfunction and send incorrect data to the engine. It controls the fuel ignition and injection timing.

• Mercedes-Benz Restraint System Malfunction Car Won’t Start

The restraint system malfunction is an issue with the vehicle’s safety systems. Your Mercedes C class won’t start because of a damaged immobilizer system. The system requires an accurately programmed key; otherwise, the engine will not start. These include the airbags or seat belt pre-tensioners. It is an anti-theft system that validates your keys to start the car.

This drive authorization system prevents theft if someone inserts the wrong key or tries to bypass the ignition. However, it can also start due to other faults with the car. For instance:

• Transmission problems such as faulty neutral safety switches do not let the engine turn.
• The engine will not start if the restraint system fails to verify the transponder chip in the key fob.
• The brake light switch may fail, preventing the restraint system from authenticating your keys.
• The gear selector module may fail, and the engine won’t turn over. You can detect a problem with the module if the shifts do not register when you move the shifter to park, neutral, or reverse.

How To Fix a Mercedes That Does Not Start When It Has Power?

To fix a Mercedes that does not start when it has power, start by jump-starting or replacing the dead car battery. You can clean the filters in the fuel delivery system or lubricate the car to ensure the engine starts. Lastly, you can replace the faulty starter or other components.

• Jump Start or Replace the Mercedes Battery

If your Mercedes car won’t start, no power will reach the battery for recharging. So you can jump-start the battery to make it work for a while, and once the car starts, the battery will begin charging. While you jump-start with another car parked near yours, ensure both vehicles are off and the cable connection is tight. Let the cars idle for a few minutes to charge your battery. After that, the engine should start, and the lights turn on.

However, you will need a new battery if your engine does not start. Buy one that is compatible with your car. They come for around $50 to $200, based on the type and quality. Clean the Clogged Fuel Filters or Replace Them If your car won’t start after replacing the battery, try cleaning the filters in the fuel delivery system. Many solutions in the market clean the blocked filters when mixed with the fuel.

However, if that does not work, you can remove the filters from the car and clean them with water and a soft brush. Sometimes the filters are so densely clogged that they need replacement. So if your engine won’t turn, you should replace the filters. They are inexpensive and cost around $10 and $50 each.

• Lubricate the Seized Engine in Your Mercedes

The engine cranks if it has proper lubrication. Poor lubrication results in losing control over the steering wheel or failure to start the engine. You can buy a good quality lubricant to add to your car or change the oil completely. Removing and adding a new and clean lubricant is better if the oil looks dark or contaminated. If your car lights turn on after a while, you do not need further diagnosis or repair.

• Repair Defective Mercedes Components

If your Mercedes has defective components, such as a bad starter motor, ignition button, or fuel system parts, you should repair or replace them. If you have a warranty, you should first contact the dealership. They will handle all problems that can prevent the car from starting.

Here’s how you can replace the starter:

• Prepare the car by parking it on a level surface and using the parking brakes.
• Disconnect the battery power by removing the negative terminal cable.
• Find the motor in the engine block and remove it by disconnecting the electrical connections. Note the position of each wire, including live, neutral, and ground cables, so that you can reinstall them later.
• Remove the motor after extracting all mounting bolts.
• Install the new motor by aligning it with the holes and inserting mounting bolts.
• Reattach the wiring harness, double-check all connections, and reconnect the battery.

Replacing a bad fuel pump can be tricky, so we advise you to get it replaced by a professional. It can cost around $300 to $800. The actual price depends on the labor cost, extra equipment required, and your decision about getting an aftermarket or OEM pump.

Conclusion

Your Mercedes has power but won’t start due to various reasons.

Here is a summary of all causes and fixes regarding this problem:

• Battery, fuse, starter, or ignition button failure prevents the car from starting.
• Obstructed fuel delivery systems or a security restraint system may prevent the latest Mercedes cars from starting.
• You can fix these issues by lubricating the engine, changing the battery, cleaning the filters, or replacing damaged components.

Taking care of these issues will restore your Mercedes so you can enjoy the rides like before.