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HomeTips & GuidesCar Trying to Start Without a Key: How to Fix a Car Starting on Its Own

Car Trying to Start Without a Key: How to Fix a Car Starting on Its Own

Visualize a scenario of your car trying to start without a key. Bizarre as it may sound, this is a prevalent problem with automobiles and can be detrimental. 

It means thieves would have a field day with your car as they don’t need the key to start it. 

So what electrical issues in your car may compel a start without its key? Pull a seat, and let’s explain this weird occurrence and how to prevent it. 

Table of Contents

Why Does My Car Start On Its Own Without a Key?

Here are some of the main reasons you’re experiencing this problem with your car. 

Issues with the Starter Motor

A Car Starter Motor. 

A Car Starter Motor. 

When one of the wires from the ignition switch experiences a power short, you’re bound to share this challenge. It also applies when a wire from the starter has a short. 

In either scenario, there’s probably a direct power connection from the relay to the car’s starter. Another probability is a situation of a shorted relay or a starter getting powered past the relay. 

Either of the three scenarios will make the car start without using its key. So to diagnose the issue, confirm if there’s power on the starting relay terminals.

If you find no current at terminal 3 of the starting relay, you’re dealing with a possible short circuit. 

Solution: Fix the faulty wire or replace the starter relay if it’s welded shut. 

Short-circuit In Fuse Box

Car Fuse Box. 

Car Fuse Box. 

A fuse is a typical protective shield that ensures your connections are safe even with an overcurrent. The rectangular fuses in your car ignition system are subject to short circuits, primarily upon contact with water. 

When this happens, there’s a high likelihood of the car starting even without the key. Therefore, an electrical short on a fuse wire or anywhere inside the fuse box is harmful. 

After-Market Accessories

One of the hacks to improve the performance of your auto is to use aftermarket parts. It is especially critical for an old car. However, accessories have their downside, especially if one buys cheap ones. 

They are subject to frequent breakdowns and can even cause short circuits leading to the car starting by itself. Hence, the rule of thumb is to keep off these low-quality/cost accessories. 

Broken Wiring

If the wires connecting to the starter solenoid are dirty or in bad shape, rest assured they can lead to electrical shorts. It, in turn, may prompt the vehicle to start by itself. 

Wonky Push Start Module or Remote Key

Car keys. 

Car keys. 

The push-start system involves using your key fob to start your car when you’re in it or a few meters away. Now a fault in this system, such as when the push button doesn’t retract, will compel the car to start independently. 

The downside of such an uncommanded start is that it may render your car moving when you’re unaware. Then it will be an easy target for thieves. Hence, fixing the problem as soon as you detect it is imperative. 

How Serious Is The Auto Start Issue Of The Car?

A burning car. 

A burning car. 

If your car starts on its own, you’re in for a series of issues that include the following:

  • A manual transmission car that auto starts is an accident hazard as it can easily knock people or bang onto structures. 
  • Also, this issue predisposes your car to car jacks and thefts as it’s way too easy to start. 
  • It’s also a substantial electrical fire hazard having such a car. 

How To Stop Car Keeps Turning On By Itself?

Here are the two primary ways to deal with a car that turns it on without your hand. 

Fixing the Ignition Switch

A Car Ignition Switch. 

A Car Ignition Switch. 

If the ignition switch is not working well, the starter solenoid will charge the starter, prompting it to switch on the engine. Hence, it would help if you fix it.

  • First, expel the cover via an Allen Wrench or other suitable tool. 
  • Next, unwrap the collars around the steering when and disconnect the ignition from its terminal. 
  • Remove the screws that hold it on its port and replace the ignition switch with another one. Screw the new switch and test to see if it works. 

Replacing the Starter Motor

A Car Starter Motor. 

A Car Starter Motor. 

When you’re sure that the issue is with the starter motor, it would help if you replaced it. But beware of using a different starter motor from the one your car is using, as this would cause starting problems. 

  • Remove the car battery to prevent electrical current from flowing during the repair. Then elevate the car using a jack to access the underside. 
  • Disconnect the negative and the positive terminals, starter wires, and wire harnesses from the starter and the battery. 
  • Now unplug the starter from its position and avoid damaging the surrounding parts. 
  • Replace it with a similar new starter. Fix the battery terminals and test if it works.  

How Much Will It Cost To Fix A Car Starter Issue?

A professional mechanic fixing a car starter motor. 

A professional mechanic fixing a car starter motor. 

On average, a starter retails between $80 and $350 but can be out of this range depending on the seller, model, and quality. Also, you must factor in the labor costs for the auto mechanic who fixes it. 

So on average, you will spend approximately $500 to fix your starter. 

But here’s a caveat; This is just an estimation, so your starter could be pricier or cheaper depending on many factors. 


Will All Cars Start Without a Key?

Some cars require you to turn on the key, while you can start others using a key nob. Starting the car without a key is hard for the latter kind, especially the modern models. 

With traditional types that use the typical key ignition system, it’s pretty straightforward to start using the hotwire method. But that becomes a challenge for new models primarily due to their locking mechanism of electronic fail-safe features. 

Can You Start a Car Without a Key?

Yes, it is possible via the conventional method of hot-wiring the ignition system. It primarily means bypassing electrical components like the key ignition lock. 

The other option is to use a mobile app, although this applies to cars that allow this feature. Finally, you can use a remote starter or start by pressing the engine button. 


If your car starts on its own without you having turned the ignition lock or the key nob, then it has a problem. You might find your auto rammed onto the garage wall in the morning. 

Hence, finding fixes for such an issue is imperative for personal safety. It also ensures your safe isn’t prone to theft. 

Hi I am Christa, sales manager of Cloom.

I have extensive expertise and experience in wiring harnesses and I believe I can help you.

And we have a very professional technical team who can clearly understand the customer’s needs and give professional suggestions and solutions after receiving the drawings.

If you also have wiring harness needs, please send me the drawing so that we can give you our quote and start our business.

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