CLAAS 7736h – ENG (A15): Fuel Temperature Input Voltage Low

The Engine Control Module (ECM) detects that the return voltage from the fuel temperature sensor is below the specified threshold (typically less than 0.5V). This electrical fault causes the ECM to interpret the fuel temperature as implausibly cold. Consequently, the system may trigger a check engine light or warning on the dashboard, reduce engine power, and limit fuel supply to protect the engine from incorrect fuel mixture calculations. Symptoms include hard starting, rough idling, reduced fuel economy, and sluggish performance.

• Arion 430-410
• Arion 640-510
• Arion 630-610 C
• Arion 650

1. 1

   Visually inspect the fuel temperature sensor wiring harness and connector for chafing, breaks, pinched wires, or corrosion.

2. 2

   Disconnect the sensor and ensure the connector terminals are clean and making a secure connection.

3. 3

   With the sensor disconnected and ignition on, measure voltage between the signal wire and chassis ground to check for a short circuit (a reading near zero volts indicates a short to ground).

4. 4

   Verify the presence of the 5V reference voltage from the ECM and check for good continuity to ground at the sensor connector.

5. 5

   Test the sensor's resistance at different temperatures and compare to manufacturer specifications to check for an internal short.

1. 1

   Repair wiring or connector

   If diagnostic checks reveal damage or a short to ground in the wiring harness or connector, repair or replace the affected section. Ensure all connections are clean, secure, and protected.

2. 2

   Replace fuel temperature sensor

   If the wiring, reference voltage, and grounds are in good condition, replace the fuel temperature sensor with a new OEM part.

3. 3

   Clear fault codes

   Use a diagnostic tool to clear the 7736h fault code from the ENG (A15) module's memory.

4. 4

   Verify repair

   Start the engine and let it run to confirm that the fault code does not reappear and that engine performance has returned to normal.