Insights
Combi boiler error codes in Warsaw flats
Photograph the display and casing label first — the same code on different brands means different things. This English table covers patterns we see in Warsaw apartment combis.
Last reviewed: Next review: Source: Editorial — manufacturer manuals + field patterns (verify on your label)Download CSV
Codes are symptoms, not diagnoses. For step-by-step first checks, see our boiler error codes guide and no hot water checklist. Smell gas? Ventilate, do not operate switches, leave the area.
Error code table
| Brand family | Code | Likely meaning | Category | Tenant DIY? | Typical action |
|---|---|---|---|---|---|
| Vaillant / Junkers | F22 / F24 | Low system pressure | Pressure | Sometimes | Check gauge (~1–1.5 bar). One careful top-up may help; if pressure drops again, suspect a leak. |
| Vaillant / Junkers | F28 / F29 | Ignition / flame failure | Ignition | No | Check hob works. No gas smell. One reset only — persistent codes need a gas-fit authorised technician. |
| Vaillant / Junkers | F75 | Pump or flow fault | Flow | No | Often pump, air lock, or blocked filter. Do not keep resetting — diagnosis needed. |
| Vaillant / Junkers | F13 / F14 | Temperature sensor fault | Sensor | No | Sensor or wiring — book service; avoid repeated hard resets. |
| Bosch / Junkers | EA / E9 | Ignition failure (series-dependent) | Ignition | No | Same as F28 — gas supply, flue, or electrode. Gas-safe technician if it repeats. |
| Bosch / Junkers | A7 | Low water pressure | Pressure | Sometimes | Top up once per manual; if gauge falls within hours, stop filling and book a leak check. |
| Immergas | E01 / E02 | Ignition failure | Ignition | No | Check gas tap to boiler. One reset; then authorised gas service. |
| Immergas | E10 | Low pressure | Pressure | Sometimes | Refill loop per manual; monitor gauge for 24h. |
| De Dietrich | F04 / AL02 | Ignition or flame loss | Ignition | No | Ventilate if gas smell. Do not cycle ignition — call gas-safe help. |
| De Dietrich | F22 | Pressure too low | Pressure | Sometimes | Single top-up; hunt for leak if pressure won’t hold. |
| Baxi / Potterton | E119 / E125 | Low pressure (model-specific) | Pressure | Sometimes | Photograph code + label — search exact model. Top up once if manual allows. |
| Baxi / Potterton | E133 | Gas supply / ignition issue | Ignition | No | Check other gas appliances. Authorised gas technician if persistent. |
| Viessmann | F2 / F3 | Flame / ionisation fault | Ignition | No | Flue blockage or gas issue possible. Stop resetting; book service. |
| Viessmann | F4 | Flow / temperature exceed | Flow | No | Pump, scale, or sensor — often needs flush or part replacement. |
| Generic combi | 504 / 505 | Pressure or flow lockout (varies) | Pressure | Sometimes | Note brand on casing — same code on different brands means different things. |
| Generic combi | Flashing display / no code | Power loss or control fault | Other | Sometimes | Check fuse/breaker for boiler circuit. If display dead, may be PCB or supply — not always plumbing. |
Before you reset
- Write down or photograph the exact code and brand/model on the casing.
- Check the pressure gauge and whether neighbours have hot water.
- One careful reset may clear a transient fault — repeated lockouts need diagnosis, especially ignition and gas codes.
- Scale and flow faults are common in medium-hard water areas.
Download
Download CSV — cite Warsaw Home Help; verify against your manufacturer manual before gas or pressure work.