Engine Protection System - High Fuel Temperature
Indicates that the fuel temperature is too high for safe operation.
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What it means (plain English)
The computer monitors the fuel temperature. If it gets above 190°F (88°C), it flags this code to protect the engine from running on hot fuel, which can cause damage.
What the computer is actually seeing
The engine control module (ECM) reads the fuel temperature from the fuel temperature sensor. If a reading exceeds the threshold (usually around 190°F or 88°C), it sets SPN 759.
What a healthy reading looks like
Fuel temperature should be between 140°F and 190°F (60°C and 88°C) during normal operation.
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 fuel temperature sensor wiring for damage or corrosion. Repair as necessary. Decision: Is wiring okay? (Yes: Go to step 2; No: Repair wiring)
- 22. Test the fuel temperature sensor with a scan tool or multimeter. Expected value is below 190°F (88°C) under normal conditions. Decision: Is the sensor reading normal? (Yes: Go to step 3; No: Replace sensor)
- 33. Check the fuel system for blockages or contamination that could cause overheating. Inspect fuel filters and lines. Decision: Is fuel system clear? (Yes: Go to step 4; No: Clean/replacement as needed)
- 44. Monitor engine operation under load and check fuel temperature again. If it still exceeds the threshold, further engine diagnostics may be required.
Common causes
- Faulty fuel temperature sensor
- Bad wiring or connectors to the fuel temperature sensor
- Excessive ambient temperatures affecting fuel tank or line temperatures
- Poor fuel quality or contaminants causing overheating
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's best to fix it soon; prolonged driving could damage the engine.
Will this code go away on its own?
Not likely; it will stay until the issue is resolved.
Why does this code keep appearing with SPN 758?
SPN 758 indicates low fuel temperature; both are related to fuel temperature sensing issues.
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