Engine Coolant Temperature High Shutdown
The SULLAIR-E002 (Sullair WS Controller / Sullair II Controller) diesel fault code means: Engine Coolant Temperature High Shutdown. This is a critical severity code.
- Keep driving?
- No -- stop driving
- DIY difficulty
- moderate
- Estimated cost
- DIY: $15-$80 for thermostat, sensor, belt, or coolant flush depending on cause. Pro shop: $150-$600 for diagnosis plus parts and labor. Head gasket or water pump replacement runs $800-$2,500 at a dealer or engine shop.
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Common Symptoms
- WS Controller LCD displays E002 and unit shuts down mid-operation
- Sullair II controller LED fault display flashes engine fault code and compressor stops loading
- Coolant temperature gauge on panel reads in the red zone before shutdown
- Unit runs normally for 20 to 40 minutes then trips off during heavy summer construction demand
- Cooling fan is spinning but unit still overheats under sustained load
- Unit restarts after cool-down period but trips E002 again within minutes of full load
- Visible steam or coolant smell near the engine compartment after shutdown
Probable Causes (Ranked by Likelihood)
- Clogged or debris-packed radiator fins reducing airflow through the core Very Likely
- Low coolant level due to slow leak at hose, clamp, or head gasket Very Likely
- Thermostat stuck closed, preventing coolant circulation through the radiator Likely
- Cooling fan drive belt slipping or broken, reducing fan speed Likely
- Faulty coolant temperature sensor sending false high reading to WS Controller Possible
- Water pump impeller worn or damaged, reducing coolant flow Possible
- Unit operating in an enclosed space or against a wall, recycling hot exhaust air back into the radiator intake Less Likely
Step-by-Step Diagnostic Procedure
Before touching anything, let the unit cool for at least 30 minutes. Never open the radiator cap on a hot engine. Personal injury from pressurized coolant is a real risk.
Check the coolant level in the overflow reservoir and at the radiator cap (cold only). Low coolant is the fastest confirmation of a leak. Top off with the correct 50/50 premix and watch for where it goes.
Inspect the radiator core and all external cooler surfaces for packed mud, construction dust, or debris. On towable units in summer dirt work, these fins clog fast. Use low-pressure compressed air from the clean side to blow debris back out the intake side. Do not use high-pressure water on a hot core.
Check the fan drive belt tension and condition. A glazed or loose belt on a belt-driven fan will let coolant temps climb under load even if everything else is fine. Belt deflection at mid-span should be roughly 1/2 inch. Replace if cracked or shiny.
Start the unit cold and watch coolant temperature on the WS Controller LCD. The thermostat should open between 180 and 195 degrees F depending on the engine spec. If temp climbs past opening point and the upper radiator hose stays cold, the thermostat is stuck closed. Replace it.
With the unit at operating temperature, feel both the upper and lower radiator hoses. Upper should be hot, lower noticeably cooler. If both are equally hot or the lower is also very hot, coolant flow through the radiator is restricted or the water pump is weak.
If coolant level, fins, belt, fan, and thermostat all check out and E002 still trips, suspect the coolant temperature sensor. On John Deere and Cummins engines, confirm the actual coolant temp using JD Service Advisor or Cummins INSITE before condemning the sensor. A sensor reading 30 or more degrees higher than actual is a clear fault. Sensor replacement is a moderate DIY swap.
If you see white smoke from the exhaust, milky oil on the dipstick, or coolant bubbling in the reservoir, stop immediately. These are signs of a head gasket failure. Do not continue to run the unit. This requires advanced engine repair.
Frequently Asked Questions
What does Sullair code E002 mean?
E002 means the engine coolant temperature climbed above the safe operating limit and the WS Controller or Sullair II controller shut the unit down to prevent engine damage. The most common reasons on rental units are a clogged radiator, low coolant, or a failed thermostat.
Can I keep running the compressor with E002 active?
No. The unit has already shut itself down when E002 trips. Do not bypass the shutdown or force a restart without finding the cause. Running an overheated diesel engine will damage cylinder heads, warp the block, or seize bearings. Find and fix the root cause first.
How much does it cost to fix E002?
If it is a clogged radiator or low coolant, you may spend nothing beyond 20 minutes with an air hose and a jug of premix coolant. A thermostat runs $15 to $40 in parts and takes about an hour. A coolant temperature sensor is $30 to $80. Water pump or head gasket repairs at a shop will run $800 to $2,500 depending on the engine.
Will the unit restart after an E002 shutdown?
The WS Controller will allow a restart attempt after the engine cools down and you clear the fault on the panel. But if the underlying problem is not fixed, it will trip E002 again within minutes of reaching full load. Clear the code, find the cause, and repair it before putting the unit back in service.