Why does my starter only click once?

Having issues starting your car? Hearing a single click when you turn the key, but then nothing happens? Don’t panic – there are some common reasons why your starter motor is only clicking once and then failing to turn over the engine. With a bit of troubleshooting, you can get to the bottom of the problem.

What’s Happening When My Starter Clicks Once?

That single click you hear when you turn the key is the sound of the starter solenoid engaging. The starter solenoid is an electromagnetic switch that connects the battery to the starter motor when you turn the ignition key. The click comes from the solenoid closing and allowing power to flow to the starter motor.

Normally, after the solenoid clicks, the starter will turn over the engine. But in your case, something is going wrong after that initial click and the starter isn’t spinning up. Let’s look at some of the possible causes:

Weak Battery

One of the most common reasons a starter motor will only click once is a weak or dying battery. The battery is responsible for delivering the power required to operate the starter. If the battery charge is low, it may have just enough power to activate the solenoid and create that click, but not enough to actually crank the motor and start the engine.

As lead-acid batteries age, they gradually lose their ability to hold a charge. Environmental factors like high temperatures can also cause faster battery drain. And if the battery was recently drained because you left the lights on or something similar, it may not have fully recovered.

Testing the battery with a voltmeter is the best way to check its condition. A fully charged 12-volt battery should have a voltage of 12.6 volts or higher. Anything less than 12 volts may be an indication that the battery is weak or failing and can no longer deliver enough amps to the starter.

Loose or Corroded Battery Terminals

In order for power to flow from the battery to the starter, there must be a clean and tight connection through the battery terminals and cables. Loose battery cables or excessive corrosion on the battery terminals can cause high resistance that restricts power flow.

When you turn the key, the initial power may allow the solenoid to click but the restriction in the cables and terminals prevents enough power from reaching the starter motor itself. The result is the single click followed by silence.

Loose battery cables can be tightened easily with a wrench. For corrosion, you may need to clean the battery posts and cable connectors with a wire brush to remove any build-up.

Faulty Ignition Switch

The ignition switch sends power to the starter solenoid when you turn the key. If this switch is worn out or damaged, it may not be making full contact and allowing complete power transfer when you turn the key.

The result can be a situation where the switch only delivers enough power for an initial click but nothing beyond that. Testing the switch with a multimeter can help determine if the contacts are faulty and if replacement is required.

Damaged Starter Motor

Of course, it’s also possible the starter motor itself has become damaged or worn out. Common causes for a faulty starter include:

  • Brushes worn – Current is transferred inside the motor via carbon brushes which wear over time. If excessively worn, they may not make proper contact.
  • Armature issues – The armature is the rotating component inside the motor. If binding, shorting or open circuits occur, it will fail to spin properly.
  • Burned out coils – Over time, the internal motor coils which generate the magnetic fields can burn out and fail.

If the motor itself is confirmed to be the root cause, then replacement of the starter is required to get back up and running.

Damaged Flywheel Teeth

The starter motor has a small gear that engages with the flywheel ring gear to spin the engine when starting. If the flywheel gear became damaged due to wear or a mechanical issue, it can cause problems with this engagement.

The starter may be able to partially engage and click, but not fully turn the flywheel due to the damaged teeth. Inspection of the flywheel gear is required to check for any broken or worn teeth issues.

How to Troubleshoot a Starter that Clicks Once

Now that we’ve covered some of the main reasons a starter will only click once, here is a summary of the basic troubleshooting steps:

  1. Check battery voltage – Use a multimeter to test battery state of charge. If low, recharge or replace battery.
  2. Inspect battery cables and terminals – Tighten any loose connections and clean any excessive corrosion.
  3. Check starter solenoid and relay – Bypass any external relays and test voltage at solenoid.
  4. Check ignition switch and safety interlocks – Confirm switches are sending proper signal to starter.
  5. Test starter motor – Bypass solenoid and supply direct power to test. Check for open/short circuits.
  6. Inspect flywheel ring gear – Check for any damaged or worn gear teeth.

Working through these basic steps methodically can help you pinpoint what component is causing the single-click issue with your starter. Make any repairs or replacements for the faulty part and your engine should be ready to start up normally again.

When to Seek Professional Help

If you don’t have automotive experience or lack the proper tools, seeking help from a professional mechanic may be the best option, especially if the issue ends up being an internal motor fault. A trained technician can efficiently diagnose the specific cause and make any needed repairs.

Seeking help right away can also be advisable if the vehicle needs to be back on the road as soon as possible. Troubleshooting electrical problems on your own can sometimes involve a lengthy process of testing and elimination.


Hearing a single click when you try to start your car is frustrating, but fortunately the range of potential culprits is limited. With methodical battery, cable, switch, and starter testing, you can get to the bottom of the no-start condition and get your engine running smoothly again.

Pay attention to battery condition and starter maintenance, and address any issues promptly to help minimize the chances of being left with that dreaded single click when you need to get going.

Possible Cause Solution
Weak battery Recharge or replace battery
Loose/corroded battery terminals Clean terminals and tighten connections
Faulty ignition switch Test and replace switch if needed
Damaged starter motor Test motor and repair or replace
Damaged flywheel teeth Inspect and replace flywheel if needed

Key Takeaways

  • A single click when trying to start usually means the starter solenoid is engaging but the motor isn’t spinning.
  • Common causes include a weak battery, loose battery cables, bad ignition switch, defective starter motor or damaged flywheel.
  • Methodically test components like the battery, cables, switches and motor to isolate the cause.
  • Repair or replace the faulty part – often the battery, starter or flywheel.
  • Seeking professional help can speed troubleshooting and get your car running again faster.

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