Troubleshooting an E-5 Oil Too Hot Error Code

Overview

Error Code: E-5 - Oil Overheat

The E-5 error occurs when the fryer detects an oil temperature above 405°F (207°C). This condition can be caused by an inaccurate temperature reading, a faulty temperature probe, a sticking heat control component, or a gas valve.

Possible Causes

• Temperature probe connection is loose, contaminated, or damaged.

• Temperature probe has failed.

• Debris buildup around the temperature probe.

• Main side gas valve coil is stuck open.

• GMU board is faulty/relay stuck closed.

• Wiring or electrical connection issues.

Call Avoidance Steps

Before dispatching a service technician, ask the customer to perform the following checks:

1. Allow the fryer to cool completely.

2. Turn the fryer OFF for 60 seconds, then restart it.

3. Verify the fryer is not overheating by comparing the displayed temperature with an independent thermometer, if available.

4. Perform the recommended deep-clean procedure to remove debris and carbon buildup around the temperature probe area.

If the E-5 error returns after these checks, schedule service.

Field Troubleshooting

NOTE: Replace parts only as required after troubleshooting.

Troubleshooting Steps

Verify Actual Oil Temperature

1. Measure the oil temperature using an independent thermometer.

2. Compare the measured temperature to the fryer display reading.

3. If the measured temperature is:

   • above 405° F (207°C), go to Check for Uncontrolled Heating.

   • significantly lower than the displayed temperature, go to Inspect Temperature Probe Connections.

Check for Uncontrolled Heating

1. Determine whether the fryer is continuing to heat when there is no call for heat.

2. Observe the burner operation and heating components.

3. If the fryer:

• continues heating without a heat call, go to Check for Constant Voltage to the Main Valve Coil.

• does not continue to heat, go to Inspect Temperature Probe Connections.

Inspect Temperature Probe Connections

1. Power OFF the fryer.

2. Inspect the temperature probe wiring and connector at the GMU board. Check for:

   • Loose connections

   • Corrosion

   • Oil contamination

   • Damaged wiring

3. If a connection issue is found, repair the connection and test operation.

Check Temperature Probe Resistance

1. Disconnect the temperature probe from the circuit.

2. Measure probe resistance.

3. Compare the reading to the expected value. Refer to 100 Ohm Chart.

4. If the resistance reading is outside specification, replace the temperature probe.

Perform Deep Clean

1. Perform the approved deep-clean procedure.

2. Ensure debris, carbon, and oil residue are removed from around the temperature probe.

3. Restart the fryer and monitor operation.

4. If the E-5 error is cleared, return the fryer to normal operation.

Check for Constant Voltage to Main Valve Coil

1. Using a multimeter, measure the voltage from the GMU to the main valve (MV) coil.

2. Check voltage when the fryer is not calling for heat.

3. If 24 VAC is present when there is no heat call, replace the GMU board.

Check for Sticking Gas Valve Coil

1. Verify whether the main gas valve remains open when power to the valve coil is removed.

2. If the gas valve coil is stuck open, replace the gas valve coil or complete gas valve assembly.

Evaluate the GMU Board

1. Verify all previous checks have passed.

2. Confirm wiring integrity and proper operation of associated components.

3. If all previous components test correctly and the fault persists, replace the GMU board.

Other Troubleshooting

Rare Cases

Intermittent Wiring Fault

Damaged wiring may intermittently affect the temperature probe signal, causing false overheat readings.

Action: Inspect the entire probe harness for pinched, damaged, or heat-damaged wiring.

Mechanical Gas Valve Failure

In rare cases, the gas valve may mechanically stick open even when the coil is operating correctly.

Action: Replace the gas valve coil or complete gas valve assembly.

GMU Board Intermittent Failure

The GMU board may fail intermittently and only exhibit the issue during heating cycles.

Action: If all other checks pass and the error cannot be duplicated consistently, replace the GMU board.