High Coolant Temperature Warning Threshold Exceeded
What does PERKINS-110-15 mean?
The PERKINS-110-15 (Kohler RDC2) diesel fault code means: High Coolant Temperature Warning Threshold Exceeded. This is a serious severity code.
Common Symptoms
- Panel displays fault code 110-15 and a warning alarm sounds
- Yellow or amber warning LED is solid or flashing on the control panel
- Coolant temperature gauge or display reads above normal operating range (typically above 100 degrees C)
- Generator continues to run but alarm is active
- PowerWizard 1.1 or 2.0 display shows 'High Coolant Temp Warning' in the fault log
- Engine may begin to feel hotter than usual near the radiator or cooling fins
- If temperature continues rising, genset will shut down automatically with a critical 110-0 or 110-1 fault
Probable Causes (Ranked by Likelihood)
- Low coolant level due to a leak or evaporation Very Likely
- Blocked or dirty radiator fins restricting airflow Very Likely
- Inadequate ventilation in the genset enclosure or room, causing hot air recirculation Very Likely
- Faulty or stuck-closed thermostat preventing coolant circulation Likely
- Coolant temperature sensor sending incorrect high readings Possible
- Failed or slipping radiator fan belt reducing cooling airflow Possible
- Water pump failure or impeller damage reducing coolant flow Less Likely
Step-by-Step Diagnostic Procedure
Step 1. Do NOT open the radiator cap while the engine is hot. Wait at least 30 minutes after shutdown before checking coolant. Opening a pressurized hot system can cause severe burns.
Step 2. Check the coolant level in the overflow/expansion tank. The level should sit between the MIN and MAX marks. If it is low, top it up with the correct pre-mixed coolant specified in your Perkins operator manual (typically 50/50 ethylene glycol and deionized water). Then inspect hoses, clamps, and the base of the radiator for visible leaks.
Step 3. Inspect the radiator fins from the outside. If dust, dirt, debris, or insects are clogging the fins, carefully blow them out with compressed air from the inside out. Blocked fins are one of the most common causes of this warning on outdoor canopied sets.
Step 4. Check the genset room or canopy ventilation. There must be a clear path for cool air to enter and hot air to exit. If the genset is in an enclosed building or container, verify that louvers and exhaust vents are fully open and unobstructed. Measure the ambient air temperature near the air intake. Ambient above 40 degrees C (104 degrees F) can trigger this warning on some ratings.
Step 5. With the engine at normal operating temperature, observe whether the upper radiator hose becomes hot and firm. If the hose stays cool even when the engine is warm, the thermostat is likely stuck closed and needs replacement. This step does not require specialty tools, only touch and visual observation.
Step 6. With the engine running, visually confirm the radiator fan is spinning and the fan belt (if belt-driven) is intact and not slipping. A squealing noise combined with a hot engine often points to a slipping belt.
Step 7. If coolant level, airflow, thermostat, and fan all appear normal, the coolant temperature sensor itself may be sending a false high reading. Use a contact thermometer or infrared thermometer to measure the actual coolant temperature at the thermostat housing and compare it to what the controller is displaying. A significant mismatch (more than 10 degrees C) points to a faulty sensor. Sensor replacement requires the Perkins EST (Electronic Service Tool) to clear calibration data on some models, so call a certified Perkins technician if you reach this step.
Step 8. After correcting the root cause, clear the fault on the PowerWizard 1.1 or 2.0 controller using the STOP button sequence, verify coolant temperature returns to the normal band (typically 75 to 95 degrees C at load), and run the genset under load for 15 minutes to confirm the warning does not return.
Frequently Asked Questions
What does Perkins code 110-15 mean?
Code 110-15 means the engine coolant temperature has risen above the warning threshold set in the controller. The genset is still running and producing power, but it is hotter than it should be. If you do not fix the underlying cause, the temperature will keep climbing and the controller will shut the genset down automatically to protect the engine. Think of it as the engine equivalent of a yellow caution light on your car dashboard.
Can my generator still run with this code active?
Yes, for now, but you should treat it as urgent. The genset will continue to run and supply power while showing 110-15, but the controller is watching closely. If the coolant temperature climbs past the critical shutdown threshold, the genset will cut off automatically. Do not ignore this warning and walk away, especially during a power outage when you are depending on the unit.
How much does it cost to fix code 110-15?
It depends entirely on the root cause. If the coolant is just low, topping it up costs $10 to $30 for coolant. Cleaning blocked radiator fins yourself costs nothing. A replacement thermostat on most Perkins engines runs $30 to $80 in parts. A fan belt is $20 to $60. If you need a professional technician for water pump replacement, coolant system pressure testing, or sensor diagnostics using the Perkins EST, expect $200 to $800 or more including labor.
Will the generator start the next time the power goes out?
A 110-15 warning alone does not lock out the genset from starting. The controller will still crank and attempt to run on the next transfer event. However, if the underlying cooling problem is still present, it will reach the warning threshold again quickly under load and then shut down on a critical fault. Fix the cooling issue now so the genset is reliable when you actually need it.