Car Won't Start? 10 Possible Causes (Quick Diagnosis Guide)

Your Car Won't Start—Let's Figure Out Why

A car that won't start can be incredibly frustrating, especially when you need to be somewhere. Before you panic, let's systematically diagnose the problem. Often, it's something simple.

Quick Diagnostic Questions

When you turn the key (or push the button), what happens?

• Nothing at all? (No sound, no lights) - Go to Section A
• Clicking sound? - Go to Section B
• Engine cranks but won't start? - Go to Section C
• Something else? - Go to Section D

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Section A: Nothing Happens (No Sound, No Lights)

1. Dead Battery

The most common cause.

Signs:

• Dashboard lights don't come on
• No interior lights
• Key fob doesn't work

Quick test: Try your headlights. If they don't work or are very dim, battery is dead.

Solution: Jump start or battery replacement.

2. Corroded Battery Terminals

Signs:

• White/green crusty buildup on battery posts
• Battery is charged but no power

Solution: Clean terminals with baking soda and water.

3. Failed Ignition Switch

If the battery is good but nothing happens when you turn the key, the ignition switch may be faulty.

Signs:

• Dashboard lights come on but car doesn't respond to key turn
• Accessories don't turn on

Solution: Ignition switch replacement: $150-$400

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Section B: Clicking Sound

4. Weak Battery

Signs:

• Rapid clicking sound
• Dashboard lights dim when trying to start

Solution: Jump start, then test/replace battery.

5. Bad Starter Motor

Signs:

• Single loud click
• Dashboard lights stay bright (not a battery issue)

Quick test: If jump starting doesn't help but lights are bright, suspect the starter.

Solution: Starter replacement: $300-$600

6. Bad Starter Solenoid

The solenoid engages the starter. Similar symptoms to a bad starter.

Solution: Usually replaced with the starter.

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Section C: Cranks But Won't Start

7. Out of Fuel

More common than you'd think, especially if the fuel gauge is inaccurate.

Solution: Add fuel. If the car has been sitting, old fuel might be the issue.

8. Fuel Pump Failure

Signs:

• No humming sound from tank when you turn key to "on" (before starting)
• Engine cranks normally but doesn't catch

Solution: Fuel pump replacement: $400-$800

9. Bad Spark Plugs/Ignition

Signs:

• Engine cranks but doesn't fire
• Might smell fuel (engine flooded)

Solution: Spark plug replacement: $100-$300

10. Clogged Fuel Filter

Signs:

• Engine sputters or hesitates before dying
• Hard starting after sitting

Solution: Fuel filter replacement: $100-$200

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Section D: Other Symptoms

Engine Starts Then Dies

Could be:

• Faulty fuel pump
• Bad idle air control valve
• Vacuum leak
• Security system issue

Grinding Sound When Starting

Starter gear not engaging properly—get it fixed before it damages your flywheel.

Car Starts Fine When Cold, Not When Hot

Could indicate:

• Failing fuel pump
• Sensor issues
• Vapor lock (rare)

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Quick Checks You Can Do

• Check the battery connections - Are they tight and clean?
• Listen for the fuel pump - Turn key to "on" and listen for humming from the rear
• Look for warning lights - Any unusual dashboard lights?
• Try different key - Key fob batteries die too
• Check the gear selector - Make sure you're fully in Park (or Neutral)

When to Call for Help

Call a mobile mechanic or roadside assistance if:

• You're in an unsafe location
• You've tried basic troubleshooting
• You're unsure about jump starting properly
• The problem persists after a jump start

Mobile Starting Diagnosis in NYC

NYC Mobile Auto Assist provides on-site diagnosis for starting problems. We'll identify whether it's your battery, starter, alternator, or something else, and can perform most repairs right at your location.

Stuck in NYC? We'll come to you and get you running.