What is the most common cause?

The single most common cause is low coolant, often from a leak in a hose, the radiator, or the water pump. Also worth ruling out: a thermostat stuck closed, trapping hot coolant in the engine, and a failed water pump that is no longer circulating coolant. Do not keep driving an overheating engine. Let it cool, top off coolant if it is low and you have some, and have the cooling system checked before driving any distance.

What can I check myself first?

Start with the safe checks: pull over safely and shut the engine off to let it cool. Then never open the radiator cap while the engine is hot. Anything beyond that is worth leaving to a shop.

Pull over when safe

Why is my car overheating?

Overheating means the cooling system is not carrying heat away from the engine. It is one of the faster ways to cause real engine damage, so the safe move is to stop rather than push on. The cause is usually low coolant, a stuck thermostat, or a cooling part that has failed.

Most likely causes

Ranked from most to least common.

1Low coolant, often from a leak in a hose, the radiator, or the water pump
2A thermostat stuck closed, trapping hot coolant in the engine
3A failed water pump that is no longer circulating coolant
4A radiator cooling fan that is not turning on
5A blown head gasket in more serious cases

What you can check

Safe, simple things to look at yourself.

Pull over safely and shut the engine off to let it cool
Never open the radiator cap while the engine is hot
Once fully cool, check the coolant reservoir level
Look under the car for a green, orange, or pink puddle

What to do next

Do not keep driving an overheating engine. Let it cool, top off coolant if it is low and you have some, and have the cooling system checked before driving any distance.

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Other things drivers ask about

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All car symptoms

Sources & further reading

NHTSA — Vehicle safety & recalls — check whether a symptom traces to an open recall, free
FTC — Auto repair basics — your consumer rights at the repair shop
AAA — Car repair and maintenance costs — independent guidance on what repairs should cost

Cost ranges and guidance reviewed July 2026.

Keep exploring

What the fix typically costs

Related trouble codes

P0128: Coolant Thermostat Below Regulating Temperature

Car Overheating FAQ

Common questions

Why is my car overheating?
Overheating means the cooling system is not carrying heat away from the engine. It is one of the faster ways to cause real engine damage, so the safe move is to stop rather than push on. The cause is usually low coolant, a stuck thermostat, or a cooling part that has failed.
What is the most common cause?
The single most common cause is low coolant, often from a leak in a hose, the radiator, or the water pump. Also worth ruling out: a thermostat stuck closed, trapping hot coolant in the engine, and a failed water pump that is no longer circulating coolant. Do not keep driving an overheating engine. Let it cool, top off coolant if it is low and you have some, and have the cooling system checked before driving any distance.
What can I check myself first?
Start with the safe checks: pull over safely and shut the engine off to let it cool. Then never open the radiator cap while the engine is hot. Anything beyond that is worth leaving to a shop.

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