Excessive Engine Coolant Temperature
The engine coolant temperature is above the expected range.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The engine is getting too hot; it's signaling the computer that the coolant temperature has gone over a safe level, often around 230°F (110°C) or more.
What the computer is actually seeing
The engine control module (ECM) reads the engine coolant temperature sensor (ECT) input. If the voltage signal is too high (usually above 4.5V), it interprets that as an excessive temperature.
What a healthy reading looks like
Normal coolant temperature is typically between 180°F (82°C) and 220°F (104°C).
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Check coolant level in the reservoir and radiator. Ensure it’s within the proper range. Decision Point: If low, top off with the right coolant type and check for leaks; if full, proceed to step 2.
- 22. Inspect the ECT sensor wiring and connector for damage or corrosion. Use a multimeter to check for proper resistance values (around 2.5kΩ at 75°F/24°C). Decision Point: If damaged, repair or replace the wiring/connector; if good, proceed to step 3.
- 33. Test the thermostat by monitoring coolant temperature; it should open around 195°F to 210°F (91°C to 99°C). Decision Point: If stuck closed, replace the thermostat; if it operates correctly, proceed to step 4.
- 44. Check if the cooling fan is operating properly when the engine temperature rises above 220°F (104°C). Decision Point: If the fan isn’t turning on, test the fan relay and wiring; replace components as necessary.
Common causes
- Low coolant level
- Faulty thermostat stuck closed
- Bad ECT sensor
- Blocked radiator
- Cooling fan not operating
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code active?
No, driving could cause engine overheating and potential damage.
If I fix the coolant level, will it come back?
If the underlying issue like a faulty thermostat or sensor isn't fixed, it likely will.
Why am I getting this with a coolant leak?
A coolant leak leads to low levels, which raises engine temperature past normal, triggering this code.
Working a real vehicle right now?
Let DiagCoach walk you through it live with your specific symptoms, vehicle, and what you've already checked.
Start guided diagnostic →