Engine Coolant Temperature High Warning

Common Symptoms

• Instrument cluster displays fault code 110-15 or a high-coolant-temperature warning lamp lights up
• Engine power noticeably drops or feels sluggish under load as the ECM begins to derate
• Coolant temperature gauge climbs above normal operating range and stays elevated
• Fan speed increases audibly as the cooling system works harder
• AGCO EDT live data shows coolant temp sensor reading above 105 degrees C
• Tractor may eventually trigger a more severe shutdown fault if temperature keeps climbing
• In cab-equipped models the operator alert buzzer may sound alongside the warning lamp

Probable Causes (Ranked by Likelihood)

• Clogged or debris-blocked radiator and/or intercooler cores reducing airflow Very Likely
• Low coolant level from a slow leak at a hose, water pump seal, or head gasket seep Very Likely
• Faulty or stuck-closed thermostat preventing coolant circulation Likely
• Failed or slipping viscous fan drive not pulling adequate airflow at operating temperature Likely
• Coolant temperature sensor out of calibration or failing, sending a falsely high reading to the ECM Possible
• Water pump impeller worn or damaged, reducing coolant flow rate Possible
• Head gasket failure allowing combustion gases into the cooling system Less Likely

Step-by-Step Diagnostic Procedure

1. Stop work and let the engine idle for 2-3 minutes before shutting down. Never open the radiator cap on a hot engine. Wait at least 30 minutes before inspecting the cooling system.

2. Check the coolant level in the overflow reservoir and at the radiator cap with the engine cold. The level should sit between MIN and MAX marks. Top up with the correct premixed coolant (50/50 OAT-type unless your operator manual specifies otherwise) if low, then look for the source of the loss.

3. Inspect the radiator, intercooler, and oil cooler cores for packed chaff, dirt, or crop residue. Even a thin mat of debris on the front face can cut airflow by 40 percent or more. Use low-pressure compressed air or water from the back side of the core, not a high-pressure washer directly on the fins.

4. With the engine fully warmed up and at idle, carefully observe the viscous fan. It should be turning briskly and pulling air through the radiator. A fan that spins freely and quietly at operating temperature, or that you can slow noticeably with light finger pressure on the blade tip when the engine is OFF and cooling down, likely has a failed drive unit.

5. Remove the thermostat and inspect it. Drop it in a pot of water heated to the opening temperature stamped on the valve body (typically 83-87 degrees C for AGCO Power engines). It should begin opening within a degree or two of that temperature. Replace it if it stays closed or opens partially.

6. Connect AGCO EDT and read the live coolant temperature sensor value. Compare it against a separate infrared thermometer aimed at the thermostat housing. If the sensor reads 15 degrees C or more above the infrared reading, the sensor itself may be drifting. Sensor resistance at 80 degrees C should be approximately 200-300 ohms on most AGCO Power applications. Consult the engine service manual for the exact curve.

7. If coolant level keeps dropping with no visible external leak, perform a cooling system pressure test with a hand-pump radiator pressure tester. Pressurize to the cap rating (typically 1.0-1.2 bar) and watch for a drop over 2 minutes. A drop points to an internal or hidden external leak. Check the oil dipstick for a milky or frothy appearance, which can indicate combustion gas or coolant mixing in the crankcase. This step requires a shop to diagnose further.

8. If all physical checks pass and the fan, thermostat, and coolant level are good, use AGCO EDT to check for any active CAN communication faults or ECM calibration issues. A dealer technician with AGCO EDT access may need to perform a coolant sensor recalibration or ECM parameter review if the code persists with no mechanical cause found.

Frequently Asked Questions