In this article, you’ll find the five most common fault codes for the Rendamax R0000 and R1000 EVO commercial boilers, what each code means and the steps required to resolve the issue.
The Rendamax R0000 and R1000 EVO are essentially the same boiler, with the main difference being that the R0000 is a floor-standing model, while the R1000 is wall-mounted.
Please note that any work carried out on a commercial boiler must only be undertaken by a qualified Gas Safe registered engineer. If you require an experienced engineer who specialises in Rendamax boilers, please contact us to arrange a site visit. Our team is also available to provide technical support and advice whenever you need assistance.
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Top 5 Rendamax R0000/R1000 EVO Fault Codes and What They Mean
| Fault Code | Definition | Quick Checks | Causes | Solutions |
| 118 1 | Sensor Plausibility (Engine 1) | Reset boiler, Check system pressure is correct, Ensure circulation pump is running, Inspect flow & return sensor plugs, Check wiring for damage/corrosion/loose connections, Bleed air from system if needed | Faulty flow or return temp sensor, Poor circulation/airlock in system, Loose or damaged sensor wiring, Dirty filter or blocked system component, Incorrect sensor readings due to hydraulic imbalance, PCB input fault | Reconnect/repair wiring and sensor connections, Replace faulty return or flow sensor, Restore proper circulation, Replace PCB if sensor inputs are defective |
| 501 1 | Flame Failure/No Flame Detection | Reset boiler, Check gas supply is ON, Confirm other gas appliances are working, Check boiler gas isolation valve is open, Inspect ignition electrode & flame sensor, Check flue & air intake are clear, Check condensate drain is not blocked | No gas supply or low gas pressure, Faulty or dirty ignition electrode, Faulty flame detection electrode, Poor earthing/electrical grounding issue, Gas valve not opening correctly, Fan/air supply issue affecting ignition | Restore gas supply/correct gas pressure, Clean or replace ignition/flame electrodes, Repair wiring/earth connection issues, Clear flue or condensate restrictions, Replace gas valve or PCB if ignition control fails |
| 612 1 | Fan Speed/Fan Proving Fault | Reset boiler, Check fan starts during ignition, Inspect fan wiring and plugs, Check for loose or damaged connectors, Ensure air intake/flue is not blocked, Check condensate drain for blockage, Listen for noise or seizes fan bearings | Faulty fan motor or fan speed sensor, Loose or damaged wiring connector, Blocked flue or air intake, Condensate restriction affecting airflow, PCB fan control fault | Repair wiring or reconnect plugs, Clear flue/air intake and condensate blockages, replace faulty fan assembly, Replace PCB if fan control signal is defective |
| 303 1 | Safety chain/interlock fault | Reset boiler, Check emergency stop is not activated, Verify all external interlocks are closed (BMS/room thermostat), Check high-limit thermostat has not tripped, Inspect safety wiring and connectors on Engine 1, Check gas pressure switch circuit is closed | Tripped high-limit safety thermostat, Open external interlock, Faulty safety switch, Loose or damaged wiring in safety chain, Control input/PCB fault | Reset or replace tripped safety thermostat, Close/repair external interlock circuit, Repair wiring or connectors, Replace faulty safety component, Replace PCB if safety input is faulty |
| 142 1 | Low Water Pressure Fault | Check system pressure gauge, Refill system to correct pressure, Reset boiler after topping up, Check for visible leaks in system, Bleed radiators/remove trapped air, Ensure filling loop is fully closed after use | System water leak, Pressure lost after maintenance or bleeding, Faulty pressure sensor, Expansion vessel issue, Air in system after pressure stability | Re-pressurise system, Repair any leaks, Replace faulty pressure sensor if readings are incorrect, Service/replace expansion vessel if pressure drops repeatedly |
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