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boiler service, boiler repair, emergency repair
Vaillant ecoMax Pro 18E Boiler Fault Codes
| Code | Description | Comment |
| F1 |
Ignition fault (lockout) Failed to light |
No gas; Insufficient gas; Incorrect gas valve adjustment; Electrode defect; Ignition lead defect; Electronic igniter defective; Check air inlet duct; Check connections to igniter unit |
| F4 | Ignition fault (lockout) Went out when lit | As above |
| F5 | Overheat fault | Overheat stat operated; Maximum temperature exceeded; Check thermistor connections; Air in system with thermistor at maximum setting; Faulty overheat stat connection; Check that pump is wired into appliance and not from programmer. This would cause no pump overrun |
| F6 | Central heating flow NTC fault | Flow NTC cable defective/broken NTC faulty Flow thermistor not fitted correctly |
| F10 | Central heating return NTC fault | Return NTC cable defective/broken NTC faulty Check that thermistor attached correctly to pipe. |
| F11 | No reception by main board | Connection fault between main PCB and interface; Faulty interface; Faulty main PCB (processor) |
| F12 | No reception by the local user interface | As F11 |
| F13 | Main board fault | As F11 |
| F14 | Central heating flow t° > 95° C | System fault; Possible external pump failure; Check NTC on flow Check that pump is wired into appliance and not from programmer. This would cause no pump overrun |
| F16 |
Flame detection fault (flame presence >5 s after burner stop) |
Gas valve defective |
| F17 | Power supply <170 V | Check electrical supply / polarity |
| F18 | Local user interface fault | Connections; Faulty interface |
| F19 | Central heating NTC unplugged | Check NTC connection |
| F20 | MMI software incompatible with IRIS software | Possible connection fault |
| F24 | Central heating return t° >90°C | System fault; Possible external pump failure; Check NTC on return; Check that pump is wired into appliance and not from programmer. This would cause no pump overrun. |
| F25 | Maximum temperature rise slope | Possible external pump failure; Air in system restricting movement of water. Insufficient circuit flow |
| F26 | Maximum delta t | Check NTC on return; System fault – too restrictive?; Possible pump failure |