John Deere 174 – Engine Control Unit (ECU): Fuel Temperature High / Fuel Temperature Excessively High - Most Severe Level

Fuel temperature reaches dangerously high levels above normal specifications (often exceeding 75°C/167°F or 77°C). Hot fuel loses its lubrication properties, which can lead to severe damage to the injector pump, fuel vapor lock, and decreased engine efficiency. The engine will typically enter a derate sequence or command an engine shut-off to protect itself.

• 5085E
• 5090E
• 5090EL
• 5100E
• 5065M
• 5075M
• 5085M
• 5100M
• 5100MH
• 5100ML
• 5115ML
• 5095M
• 5095MH
• 5105M
• 5015ML
• 5090M
• 5115M
• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 5M Series
• 5E Series
• 7020 Series
• 7220
• 7320
• 7420
• 7520
• 9540
• 9560
• 9580
• 9640
• 9660
• 9680
• 9760 STS
• 3520
• 3522
• 7000-series
• 75G

1. 1

   Check the fuel level: A nearly empty fuel tank can cause fuel to overheat rapidly due to continuous recirculation of hot fuel.

2. 2

   Inspect the cooling system: Check the engine coolant level and inspect the radiator for debris or blockages, as degraded cooling system performance is a primary cause.

3. 3

   Inspect the fuel cooler: Check the fuel cooler for dirt, debris, or blockages.

4. 4

   Check hoses and lines: Inspect coolant and fuel lines for any pinched hoses that might restrict flow.

5. 5

   Check for external heat sources: Identify and mitigate any nearby heat sources or missing heat shields that could be radiating excessive heat into the fuel lines.

6. 6

   Sensor verification: Use a diagnostic tool to check if the fuel temperature sensor reading matches the ambient air temperature when the engine is completely cold (DO NOT START ENGINE during this check).

1. 1

   STOP THE MACHINE immediately

   Shut off the engine, and allow the fuel temperature to cool to prevent injector pump damage.

2. 2

   Fill or switch fuel tanks

   If the fuel tank is almost empty, fill the tank (or switch fuel tanks if equipped) to introduce cooler fuel into the system.

3. 3

   Clean the radiator and fuel cooler

   Clean the radiator and the fuel cooler thoroughly with compressed air or water to restore proper airflow and heat exchange.

4. 4

   Visually inspect the fuel temperature sensor

   If the code returns after cooling and cleaning, visually inspect the fuel temperature sensor for a damaged housing, damaged O-ring, or loose pins in the wiring harness connector.

5. 5

   Replace the fuel temperature sensor

   If the sensor is physically damaged, or if diagnostic readings show it does not match ambient temperature when cold, replace the fuel temperature sensor.

6. 6

   Verify the repair

   Reconnect the battery/harness, clear the Diagnostic Trouble Codes (DTCs) via the monitor or diagnostic tool, and operate the engine under normal load to verify the repair.

7. 7

   Investigate deeper issues

   If the problem persists, the issue may require a John Deere dealer to investigate deeper fuel recirculation settings or high-pressure fuel system leaks.