JLG Telehandler 4316 Fault Code: Engine - High Engine Coolant Temperature Warning

What does JLG Telehandler error code 4316 mean?

Fault code 4316 is JLG's alert for high engine coolant temperature. The machine's controller watches coolant temperature through a sensor and, on ECM-controlled engines, also receives the reading over the J1939 CAN bus. When the temperature climbs too high, the system logs the fault and lights up multiple indicators at once: general machine system distress, a general engine fault warning, and the specific high coolant temperature indicator.

This isn't just a dashboard nuisance. Coolant temperature that reaches the fault threshold means the engine is running hotter than it should, and on ECM-controlled engines the controller may automatically derate the engine, cutting power to protect it. That derate is a built-in safety measure, but it also means reduced performance until the root cause is fixed.

The fault is reported two ways: a mechanical trigger based directly on sensed coolant temperature, and an electronic trigger where the ECM broadcasts the condition as a J1939 DM1 diagnostic message (or through the transfer protocol when other engine faults are also active) as a high engine coolant temperature warning, representing high readings at different severity levels.

What triggers a JLG Telehandler 4316 code?

The fault sets when engine coolant temperature reaches 113°C or higher for at least 10 seconds while the engine is running. On the electronic side, the ECM sets the fault when it detects coolant temperature at 113°C or more and transmits this as a J1939 CAN bus DM1 message (SPN:FMI 110:15 or 110:16) on CAN1. The fault latches active until, mechanically, coolant temperature drops back to 110°C, or electronically, until the ECM no longer transmits the condition as an active fault.

Common causes of 4316

• Low coolant level or a coolant leak reducing the system's ability to carry away heat.
• A failing or clogged radiator, or a radiator/cooling fins packed with debris, dirt, or trash restricting airflow.
• A failed or seized cooling fan, damaged fan clutch, or fan drive issue that keeps enough air from moving through the radiator.
• Faulty or failing coolant temperature sensor sending an inaccurate high reading to the ECM.
• Thermostat stuck closed, preventing coolant from circulating properly through the radiator.
• Water pump failure or worn impeller reducing coolant flow.
• Wiring or connector problems on the coolant temperature sensor circuit causing an erroneous high signal.
• Operating the machine under heavy load in high ambient temperatures beyond the cooling system's capacity.

How to troubleshoot JLG Telehandler 4316: first checks

1. 1Check the coolant level in the reservoir and radiator once the engine has cooled. Do not open a hot cooling system.
2. 2Inspect the radiator and cooling fins for mud, debris, dirt, or trash blocking airflow, and clean as needed.
3. 3Confirm the cooling fan is spinning freely and the fan clutch or fan drive is functioning when the engine is running and warm.
4. 4Look over coolant hoses and connections for leaks, soft spots, or damage.
5. 5Inspect the coolant temperature sensor and its wiring harness and connector for corrosion, damage, or loose pins.
6. 6Check that the thermostat is opening properly and coolant is circulating through the radiator.
7. 7Use a diagnostic tool to read active and stored fault codes and confirm whether the ECM is reporting a high coolant temperature fault, and check for other active engine faults that may be triggering the transfer protocol message.

How the code clears

The fault latches until coolant temperature drops to 110°C on the mechanical side, or until the ECM stops transmitting the condition as an active fault on the electronic side. No separate reset procedure is listed for this code. Once the underlying cooling issue is fixed and coolant temperature returns to normal, the fault should clear on its own as the ECM stops reporting the active condition.