We're working on a fix — Diago should be back shortly. Thanks for your patience.
Diago
Instant AI vehicle diagnostics
Diago
Instant AI vehicle diagnostics
An overheating engine is one of the few car problems that can go from inconvenient to catastrophic in minutes. A blown head gasket or warped cylinder head can turn a $200 repair into a $3,000 one. Act fast.
The most common cause. Could be a leaking hose, radiator, water pump, or head gasket. Check the reservoir level and look under the car for puddles (usually bright green, orange, or pink).
The thermostat controls coolant flow. If it sticks closed, hot coolant can’t reach the radiator to cool down. Engine overheats even with full coolant.
The water pump circulates coolant through the engine and radiator. A worn impeller or leaking seal causes coolant to stop flowing — the engine overheats even though coolant level is fine.
A clogged, bent, or leaking radiator can’t shed heat fast enough. Common on older vehicles or after front-end impacts.
At low speeds or idle, the radiator fan pulls air through the radiator. If it fails, the car runs fine on the highway but overheats in traffic.
The worst case. The head gasket seals coolant and combustion chambers. A blown gasket lets exhaust gases into the coolant, causing rapid overheating and white smoke from the exhaust.
Tell Diago your vehicle, what you’re seeing on the temp gauge, and any other symptoms (smoke, leaks, smell). Get a diagnosis with the most likely cause and what to check first — before it becomes a $3,000 repair.
Diagnose my overheating engine →Pull over and shut off the engine immediately. If you must go a short distance, crank the heat full blast — it pulls heat from the engine. Do not open the radiator cap. Wait 30 minutes, check coolant, then diagnose before driving further.
No. Even a short drive in the red can warp a cylinder head or blow a head gasket — turning a $200 fix into a $2,000–$5,000 repair. Pull over as soon as it’s safe.
White sweet-smelling exhaust smoke, milky oil, coolant disappearing with no visible leak, or bubbling in the coolant reservoir are all signs. A combustion block test on the coolant can confirm it.
Yes — select your vehicle type and Diago will tailor the diagnosis. RVs and semi trucks overheat under different conditions than passenger cars and the diagnosis reflects that.