Troubleshooting the E-20 D Gas Ignition Failure No MV Signal Error Code

Overview

E-20 D - Gas Ignition Failure, No MV Signal

This error occurs when the Gas Management Unit (GMU) commands the main gas valve solenoid to open after successful pilot ignition but does not detect the required main valve (MV) signal(s) to the GMU K3 Relay from the ignition modules.

On a full vat fryer, both MV1 and MV2 signals must be present at the same time. A hardware interlock relay (K3) combines the two signals and only allows 24VAC to pass to relay K4 when both signals are present simultaneously. This safety feature prevents the main burners from operating if only one pilot flame is established.

The MV 24VAC from the ignition modules to the GMU only occurs once the module(s) detect flame sense.

Ignition Module Sense Operation

Each ignition attempt lasts up to 90 seconds.

• The ignition modules wait to see if they receive a 1uA (microamp) signal from the flame sense.

  • If no flame is detected:

    • The pilot valve (PV) turns off.

    • The blower runs for approximately 15 seconds to purge unburned gas.

    • Upon completion of the inter-purge period, the module initiates another ignition attempt.

After the third unsuccessful attempt, the ignition module locks out and the E-20 D error is generated.

Call Avoidance Steps

Before dispatching a service technician, ask the customer the following questions and request the customer perform the following, if possible.

1. Check Gas Supply Line

It is very common that the gas supply line is either disconnected or loose, or the shut off valve is in the OFF position or not fully on. Some scenarios to determine if there is a gas supply issue can be:

• Is the E-20 D on the whole fryer displaying?

  • If the error is displayed on the whole fryer, it is likely the fryer is not receiving any gas. Make sure the line is connected properly and the gas shut off valve is turned all the way to the ON position.

  • If the gas line is connected and the valve is on all the way, verify no other gas equipment in the store is working.

    • If more than one appliance on the gas line is not working, have the store verify the building is receiving gas properly from the gas company.

• Is the E-20 D only on the far-right display?

  • Ask the customer to double check that the gas line has no kinks and the shut off valve is turned on all the way.

    • Any restriction of gas or lack of gas pressure can cause the fryer to work on the left side while preventing adequate gas flow to the far-right side.

2. Check Ignition

Can the customer hear any sparking/igniting trying to occur? If not, there could be an issue with the pilot spark rod, ignition cable, or ignition module.

3. Check Gas Valve

If possible, have the customer check the gas valve's atmospheric equalization breathing cap on the gas valve. This will require removal of the cover and cap to clean and to make sure there is no restriction causing the pilots to reduce and not sense properly.

4. Reset Ignition System

Turn power off and on (cycling power) to the fryer at the main power switch to reset the ignition sequence.

If the error remains after these checks, dispatch a service technician.

Field Troubleshooting

NOTE: Split vats work on their own system and have 1 GMU and 1 ignition module for each side.

• Example: Left side of split troubleshooting will be on the left GMU board and left ignition module. The right side of split troubleshooting will work on the right GMU and right module.

• Troubleshooting below is for full vat configurations. Troubleshooting can be completed the same way for split vat configurations but will have less parts as mentioned.

NOTE: Manually turn on the main heat signal in service mode to test.

To access service mode:

1. Enter the Settings menu on the control and select Service.

2. Enter code 1122.

3. Select Heat System.

4. Select Combustion Fan to turn the fan on and off manually first.

5. Select 24 VAC to select safeties.

6. Select Pilot Ignition button to energize the PV step.

7. Once pilots sense, select Heat Valve to energize and test the MV outputs and main burn.

Troubleshooting Steps

Verify Error Condition

1. Confirm the displayed error is E-20 D.

2. Reset the ignition sequence.

3. Observe the complete ignition cycle. If the fryer ignites normally, troubleshooting is complete.

Verify Gas Supply

1. Confirm the manual gas shutoff valve is open and the gas supply line is connected properly.

2. Using a manometer, verify gas is available to the appliance.

   • Natural gas incoming to the fryer should be: 7 wc and 3.5 wc at the burner manifold.

   • Liquid propane to the fryer should be: 10 wc at the burner manifold.

3. Confirm other gas appliances in the facility are operating normally if applicable.

4. If gas supply is not available, restore gas service and retest.

Check Pilot Ignition

1. Start an ignition cycle.

2. Observe whether the pilot flame establishes successfully. If the pilot flame does not ignite, troubleshoot the ignition system:

   • Spark electrode

   • Pilot gas circuit

   • Ignition module

3. After repair, retest.

Check GMU Board Inputs from Ignition Modules

1. Verify all GMU connectors are fully seated.

2. Inspect the GMU board for:

• Burned components

• Damaged traces

• Corrosion

3. Verify GMU is receiving 24 VAC from the ignition modules on the J23 connection, MV1-L and MV2-R (blue) wires separately to ground.

   • If 24 VAC is being received to the GMU on both MV1 and MV2 and not being sent out to the gas valve coil, replace GMU.

   • If there is no voltage on either MV1 or MV2 wires on the GMU side, verify the MV outputs of the left and right ignition modules.

     • If the ignition module is sending voltage out, verify connections and wiring. Replace if needed.

     • If ignition module is not sending voltage out, verify the flame sense harness is connected and sensing properly. Replace module if needed.

   • If 24 VAC on only MV1 (left ignition module) or MV2 (right ignition module) trace back to the proper ignition module, verify the module is sending 24 VAC out.

     • If ignition module is sending voltage out, verify connections and wiring. Replace if needed.

     • If ignition module is not sending voltage out, verify the flame sense harness is connected and sensing properly. Replace module if needed.

Other Troubleshooting

Flame Established but Not Recognized

The burner may ignite, but the control does not receive proper flame feedback.

• Clean the flame sense electrode.

• Verify grounding.

• Replace the flame sense electrode if necessary.

Recent Service or Cleaning Activity

Wiring or connectors may have been disturbed during maintenance.

• Inspect recently serviced areas.

• Verify all harnesses and terminals are connected correctly.