Troubleshooting and fixing fault code L04/F04 “Flow Thermistor Fault”
on your Ideal Logic2+ Combi Boiler
If you own an Ideal Logic2+ Combi Boiler, you may come across various error codes that indicate potential issues. One such error code is L04/F04, which signifies a “flow thermistor fault.” In this blog, we will delve into the details of this fault, explore red flags to look out for, provide troubleshooting tips, and discuss what actions you can take both as a homeowner and as an engineer to resolve the issue.
What is a Flow Thermistor Fault?
The L04/F04 fault on the Ideal Logic2+ Combi Boiler refers to a flow thermistor fault. The flow thermistor is a temperature sensor responsible for monitoring the temperature of the water flowing through the boiler’s heat exchanger. If the flow thermistor detects an abnormal reading or fails to provide accurate temperature information, the boiler triggers this fault code.
L04/F04 Red Flags!
Loss of hot water
Inconsistent water temperature
Error code display
The boiler repeatedly shutting down
Reduced heating performance
Check out what your allowed to do:
Homeowners – What you can do as a homeowner?
Qualified Gas Engineers – Troubleshooting Tips, And What to Do as a Qualified Gas Engineer?
L04/F04 Troubleshooting Tips:
Power cycle the boiler: Turn off the power supply to the boiler and wait for a few minutes. Then, turn it back on. This simple reset can sometimes clear temporary faults and reset the system.
Check water pressure: Ensure that the water pressure in your heating system is within the recommended range. Low water pressure can trigger fault codes, including the L04/F04 error. If the pressure is low, consult your boiler manual for instructions on how to repressurize the system.
Inspect external factors: Examine the pipework, valves, and filters connected to the boiler for any visible signs of damage or blockages. Remove any debris or obstructions that might be hindering the flow of water.
Verify thermostat settings: Make sure the thermostat on the boiler is set correctly. Check that it is set to the desired temperature and mode (e.g., heating or hot water). Incorrect thermostat settings can sometimes cause errors.
Check electrical connections: Inspect the wiring connections around the flow thermistor and other relevant components. Ensure they are securely connected and free from any loose or damaged wires.
Monitor other error codes: Take note of any other error codes that may be displayed alongside the L04/F04 fault. Additional error codes could provide further insights into the underlying issue and help narrow down the troubleshooting process.
What can you do as a Homeowner?
As a homeowner, you can take certain steps to address the L04/F04 fault:
- Power cycle the boiler: As mentioned earlier, try turning off the power supply to the boiler, waiting for a few minutes, and then turning it back on. This simple reset can sometimes clear temporary faults.
- Check water pressure: Verify that the water pressure in your heating system is within the recommended range. Low water pressure can trigger fault codes, including L04/F04. Consult your boiler manual for instructions on how to check and adjust the water pressure if necessary.
- Inspect for visible issues: Look for any obvious signs of damage, blockages, or leaks in the visible parts of the boiler, such as pipework, valves, and filters. If you notice anything concerning, take note of it and mention it to the engineer when they arrive.
- Check warranty coverage: If your boiler is still under warranty, review the terms and conditions of the warranty. Some faults, including the L04/F04 fault, may be covered by the warranty, and the manufacturer may arrange for repairs or replacement at no cost to you. Contact the manufacturer or warranty provider to initiate a warranty claim if applicable.
- Document the fault: Keep a record of any error codes, symptoms, or observations related to the L04/F04 fault. This information will be useful when communicating with customer support or a qualified engineer. It can help them understand the issue better and expedite the troubleshooting process.
- Follow safety precautions: While troubleshooting, always prioritise safety. Turn off the power supply to the boiler before attempting any manual checks or repairs. If you’re unsure or uncomfortable with any steps, it’s best to leave the work to a trained professional.
What to do as a Qualified Gas Engineer?
If you are an engineer or a qualified professional dealing with the L04/F04 fault, here are some suggested actions:
- Gather information: Begin by speaking with the homeowner to understand the symptoms they’ve observed, the frequency of the fault occurrence, and any recent changes or incidents that may have preceded the fault.
- Inspect the boiler: Conduct a thorough visual inspection of the boiler, focusing on the flow thermistor, wiring connections, and associated components. Look for any signs of physical damage, loose connections, or visible faults.
- Check resistance of the flow thermistor: Use appropriate diagnostic tools, such as a multimeter, to measure the resistance of the flow thermistor. Compare the measured resistance with the manufacturer’s specifications to determine if the thermistor is within the acceptable range.
- Verify wiring connections: Ensure that all wiring connections related to the flow thermistor and associated circuitry are secure and properly connected. Address any loose or damaged wires as necessary.
- Replace the flow thermistor: If the flow thermistor is found to be faulty or outside the acceptable resistance range, it may need to be replaced. Follow the manufacturer’s guidelines and use genuine spare parts to maintain the integrity of the boiler.
- Conduct system tests: Perform tests on the heating system, including checking the operation of the heat exchanger, pumps, and valves. Ensure that they are functioning correctly and not contributing to the fault.
- Clear blockages and debris: If any blockages or debris are identified in the pipework or filters, clean or remove them to restore proper water flow and prevent further issues.
FAQ's
Yes, performing a power cycle by turning off the boiler and then turning it back on after a few minutes can sometimes clear temporary faults, including the L04/F04 error code.
The L04/F04 fault is not inherently dangerous. However, it indicates an issue with the flow thermistor that can impact the boiler’s performance. It is important to address the fault to ensure proper functioning and prevent potential long-term damage.
As a homeowner, it is recommended to consult a qualified engineer or contact the boiler manufacturer’s customer support for guidance. Attempting repairs without proper knowledge and expertise may lead to further complications or void the warranty.
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More help & advice:
Take a look at more of our Ideal Logic 2+ combi boiler fault and error codes.
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