Car Won’t Start When Engine is Hot [Causes & What To Do]

The car engine is a crucial component in your automobile. The engine is the “heart of a car” because it converts the heat from burning gasoline into the force that keeps your car in motion.

Just as your body won’t function well when you have a problem with your heart, the engine can also not perform well if there is a problem with it.

Therefore, if your engine is hot and won’t start, it simply shows there is a problem with some other components, such as the fuel system, battery, etc.

To find out why your car won’t start when the engine is hot, read this post till the end as we explain the possible causes and how to resolve them.

car engine hot

What Causes the Car Not to Start When Engine is Hot?

1. Faulty Car Battery Terminal

Normally when a car won’t start, the first suspect is the battery. Because without the battery, your car starter, which is the component that starts your car, won’t be able to function–it draws power from the battery to work.

Therefore, when your car fails to start or experiences a hard start due to a hot engine, you need to inspect the battery terminal or connection as well as the battery.

Damaged and corroded battery connections prevent energy from reaching the starter, which is why your automobile struggles to start when the engine is hot.

Although a small amount of corrosion may not prevent the car from starting, it will quickly spread throughout the car battery, which can also cause your car to not start.

Corrosion hides in connectors, making it difficult to remove or clean corrosion from connectors. It is critical to avoid corroded battery terminals and loose battery cable connections.

Signs of a Faulty or Corroded Battery Terminal

  1. Electrical power failure.
  2. Hard starting
  3. The vehicle won’t start
  4. Starter motor breakdown

2. Low Engine Coolant

Having a low coolant can not only cause your engine to overheat or your gasket to get damaged. It can also cause your car to shut off.

Coolants transmit and regulate heat in the engine by providing antifreeze protection to ensure that your vehicle’s engine runs at peak performance.

Therefore, when you have confirmed your battery is intact, you need to check your coolant level–make sure your car is cool before opening the coolant cap.

Symptoms of Low Engine Coolant

  1. The temperature gauge will keep rising
  2. Poor fuel economy
  3. The engine shuts down automatically
  4. Warning light on your car dashboard
  5. Heating system failure.

3. Faulty Starter Motor and the Circuit

The starter motor plays a vital role in getting your car started. When you start your car or push the start button, the battery voltage passes through the starter control circuit and triggers the starter solenoid.

The starter motor spins and turns the engine crankshaft, allowing the engine to start.

However, when your engine temperature is high, it makes this condition more challenging by increasing electrical circuit resistance.

Which will result in your car not starting. Identifying the car’s starting motor and circuit problem is always not an easy one difficult.

When the starting fails, the engine should make clicking, grinding, or whirring noises.

Therefore, whenever you observe a clicking or whirring noise in your automobile, we recommend you contact a good professional.

4. Camshaft or Crankshaft Position Sensor Failure

A car’s camshaft and crankshaft position sensors are linked to the ECM. They are in charge of providing the piston data required to run the fuel injector and spark plug at peak performance.

However, the car engine becomes warm when the camshaft or crankshaft fails to communicate with the engine control unit.

Malfunctioning camshaft and crankshaft position sensors disrupt the operation of the fuel injector, causing the engine to overheat and making it difficult to start.

Symptoms of a Faulty camshaft or crankshaft position sensor

  1. Engine vibration is excessive.
  2. The car’s engine stops.
  3. Your car will have difficulty starting.

5. Vapor Lock

This is another factor that can prevent your car from starting when the engine is hot. A vapor lock occurs when fuel vaporizes before entering the combustion chamber.

When the fuel in your car boils in the fuel line, the evaporated fuel causes back pressure in the automobile fuel system, stopping the gas from entering the engine.

This vapor will then mix with the fuel and flow out of the tank, causing engine efficiency issues and making your car difficult to start when hot.

Symptoms of Vapor Lock in Automobiles

  1. The engine won’t start
  2. Loss of power
  3. Loss of fuel pressure
  4. No starting

6. Clogged Filter

Air filters help to create cool air for your engine. It keeps dust, particles, sand, and debris out of the engine and promotes a good air-to-fuel ratio.

However, when your air filter is clogged or obstructed, your vehicle will get heated and this can hinder your automobile from starting.

Dust, particulates, and debris can clog an air filter over a lengthy period of use. That is why, if your automobile won’t start after the engine is turned off, you should inspect and clean the air filter.

Symptoms of a Clogged Air Filter

  1. Reduced gas mileage.
  2. Noise from the engine
  3. Hard starting
  4. A strong smell of gasoline.
  5. poor acceleration

7. Loose or Corroded Engine Ground Connection

A stable ground connection is critical to the effective running of your engine. If the cables become loose or rusted over time, the increasing circuit resistance might cause problems.

Not only may the starting system be compromised, but other electrical components may also be impacted. A terrible ground, on the other hand, is difficult to detect visually.

Symptoms of Corroded or Loose Engine Ground Connection

  1. Increased resistance to actuators and sensors
  2. Having trouble starting the engine
  3. Problems with the automatic transmission

What Should I do if my Car Won’t Start When the Engine is Hot?

  1. Clean your air filter
  2. Check the engine coolant level and refill if it is low
  3. Repair or replace a faulty battery/cables
  4. Replace failed crankshaft position sensor

Read: Car AC Not Cold When Idle?


Having your car not start when the engine is hot is not a pleasant experience. This issue could probably be a result of low-engine coolant. If your car does not have enough coolant, it causes overheating, and this can make your car not start. 

A faulty starter motor or circuit is another reason why you might find it difficult to start your car when the engine is hot.

A damaged battery is also a major cause. When you have been able to identify the cause of this issue in your vehicle, fixing it would not be difficult.

Note that, if you see the check engine light illuminated, you can diagnose it with an OBDII scanner.