Troubleshooting the E-20 C Pilot Valve Signal Not Detected Error Code

Overview

E-20 C - Pilot Valve Signal Not Detected

This error occurs when the Gas Management Unit (GMU) commands the pilot valve to open during the ignition sequence but does not detect the required Pilot Valve (PV) 24VAC feedback signal within 20 seconds on the GMU.

The ignition sequence requires the control to see valid PV signals from the ignition circuit. If the PV signals never appear, the fryer generates E-20 C.

Common causes include:

• Failed ignition module.

• Disconnected ignition module or wiring.

• Loose or faulty ignition cable.

• Failed safety relay (K1) on the GMU.

• Failed TH relay (K2) on the GMU.

• Ignition module detecting a false flame signal from flame sensor and refusing to start ignition.

• Open or damaged wiring harness.

Call Avoidance

Before dispatching a service technician, verify the following:

1. Cycle fryer power OFF for 30 seconds, then power ON.

2. Observe the fryer during start-up:

   • If sparking is present when control is turned on to start heating, this is typically not an E-20 C condition when sparking is present.

   • If no ignition attempt occurs and E-20 C appears, service is likely required.

3. Verify if the error is on a full vat or split vat.

   • If split vat, verify if the issue is on both sides or one side.

Field Troubleshooting

NOTE: The pilot ignition signal can be manually turned on in the 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.

5. Select 24 VAC to select safeties.

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

Recommended Parts

• Ignition module

• GMU board

• Flame sensor

• Ignition cable

Recommend Tools

• Digital multimeter

• Basic hand tools (screwdrivers, nut drivers, etc.)

Troubleshooting Steps

IMPORTANT: Before troubleshooting, verify if only one or both igniters are trying to spark. This following list should narrow down troubleshooting.

FULL VAT

• If both igniters are sparking, voltage is being sent from the GMU to both ignition module TH 24 inputs and the PV is coming from the left ignition module.

  • GMU may not be seeing the 24 VAC from the right ignition module.

• If only the left pilot is sparking, the left ignition module is receiving the 24 VAC from the GMU but may not be receiving the PV voltage back from the left ignition module.

  • Other quick checks are:

    • Verify the right ignition cable is connected properly.

    • Check ignition failure light codes for more information.

  • This issue may require further troubleshooting on the GMU and ignition modules.

• If only the right pilot is sparking, voltage is getting to both ignition modules from the GMU to the TH and PV is coming back to the GMU from the left ignition module.

  • Left igniter cable may be loose or disconnected.

SPLIT VAT

The above quick checks and troubleshooting can also be applied to split vats, but each side will be its own system. A split vat will operate on only one ignition module for each side and each side has its own GMU.

Verify Relay K1 Operation (CE Fryers Only)

1. Start an ignition cycle.

2. Measure voltage at the CE Safety Valve.

   • If 24 VAC is not present, check wiring and if it is good replace GMU.

Verify Relay K2 Output

1. (Full Vat Only) During ignition, verify if neither side igniters spark or only the left pilot sparks.

   • If only the left pilot sparks, go to Relay K2 Output.....

2. During ignition, on the GMU Board J23 connection measure the 24 VAC of Relay K2 output on TH1-L (red wire) to ground for full vat or left side of split vat.

   • If voltage is present at the GMU side, verify voltage is being supplied to the left ignition module TH input.

   • If voltage is present at the GMU and not at the ignition module, verify wiring is not damaged and replace if needed.

   • If voltage is not present at the GMU, replace GMU Board.

   • If voltage is present to the TH on the ignition module and the left pilot is to sparking before replacing the ignition module, verify ignition cable is not loose, disconnected, or shorted.

   • Check the output 24 VAC on the PV1-L (yellow) wire on the ignition module to ground.

     • If no 24 VAC output from the ignition module is present, replace left ignition module.

     • If 24 VAC is present at ignition module, but not at the GMU, verify wiring is not damaged and replace if needed.

3. If only the left pilot sparks, this means the K2 relay output on the GMU to left ignition module is good, but there may be a loss of 24 VAC to the GMU or GMU to right ignition module or the right ignition spark cable is loose, faulty, or not connected.

If the ignition spark cable is good:

• Verify the GMU is receiving 24 VAC back from the left ignition module's PV output on the PV1-L (yellow) wire.

  • No 24 VAC out of the ignition module on PV1-L (yellow) wire, replace ignition module.

• If 24 VAC is preset out of the left module and back to the GMU, check for 24 VAC out of the GMU on TH2-R (red) wire to the right ignition module.

  • No 24 VAC out of GMU, replace GMU.

  • 24 VAC is out of GMU, but not at module, check for loose or damaged wiring and replace if needed.

  • If 24 VAC is getting to the TH 24V line on the right ignition module, double check spark ignition cable and replace right ignition module if needed.

Other Possibilities

CE Safety Valve Issues (CE Models Only)

The CE safety valve receives power through relay K1. A failed valve coil or wiring fault may affect the 24 VAC circuit.

• Verify 24 VAC is present at the valve when K1 energizes.

• Swap coil with a working coil and test.

• Replace coil if faulty.

Check for False Flame Detection

Inspect the flame sense electrode for:

• Shorted electrode

• Grounded flame sensor wire

• Moisture contamination

• Carbon tracking

• Damaged insulation

The ignition module may refuse to start ignition if it falsely senses a flame already exists.

Intermittent Harness Failures

Vibration, heat, or previous repairs may cause intermittent opens.

• Perform a wiggle test on wiring harnesses.

• Inspect connectors for corrosion, overheated terminals, or loose pins.

Grounding Problems

Poor grounding can cause unreliable ignition module operation.

• Verify chassis ground connections are clean and secure.

• Repair any corroded or loose ground points.

Multiple Component Failures

If rare cases, more than one failure may exist simultaneously.

Examples:

• Failed K2 relay and damaged ignition module.

• False flame condition and wiring damage.

• Intermittent harness fault and weak relay contacts.

If troubleshooting results do not follow the expected sequence, verify each step independently and confirm circuit operation before replacing additional components.