Engine Temperature High
Indicates the engine coolant temperature is above normal operating levels.
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's coolant temperature sensor is reporting that the engine is overheating—say, above 240°F.
What the computer is actually seeing
The Engine Control Module (ECM) measures the resistive voltage signal from the coolant temperature sensor. A normal operating range would be around 190°F to 220°F; anything above 240°F can trigger this code.
What a healthy reading looks like
Expected voltage from the sensor is about 0.5V to 4.5V depending on the temperature; at 200°F, you should see around 2.5V.
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 the engine coolant level. If it's low, refill and check for leaks. Decision: Is coolant level okay? Yes: Go to step 2. No: Refill and retest after addressing leaks.
- 22. Inspect the wiring and connector to the coolant temperature sensor for damage or corrosion. Decision: Is wiring intact and connector tight? Yes: Go to step 3. No: Repair wiring/connector and retest.
- 33. Use a scan tool to monitor the engine coolant temperature. Compare the reading with a laser thermometer at the coolant outlet. Decision: Is the ECM reading accurate to your manual measurement? Yes: Go to step 4. No: Replace the coolant temperature sensor and retest.
- 44. Check thermostat operation by monitoring engine temperature rise. Verify it opens at specified temp (usually around 195°F). Decision: Is the thermostat functioning? Yes: Go to step 5. No: Replace the thermostat and retest.
- 55. Inspect the radiator and cooling fan operation. Ensure the fan engages at the correct temperature. Decision: Is the cooling system functioning as expected? Yes: If all else checks out, possible ECM fault. Replace ECM or consult dealer. No: Repair cooling fan issue and retest.
Common causes
- Failed coolant temperature sensor
- Low coolant level
- Coolant leak
- Faulty thermostat
- Cooling system blockage
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
No, driving can cause engine damage due to overheating.
Will this code come back even after repairs?
If the underlying issue is fixed properly, the code should not return.
Why might this code be paired with low coolant?
A low coolant level can trigger an overheat condition, causing this code to set.
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