Truma Combi error code W 21 H
Plausibility of NTC Room Temperature Sensor. Room Temperature Sensor outside tolerance range - sensor/harness, excessive temp.
What to check, and in what order, is in the app. The flow Truma Combi — Heater Overheat / Code 0094 / 0150 walks this code step by step with the pass/fail measurements, wiring schematics and procedures that go with it, and it works offline in the bay.
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- Truma Combi Service HandbookTruma
- Truma Combi Service Handbook (TrumaCorp, 20 pp; technician training handbook with Common Error Codes table and per-code Further Details sections) (rv-tech-resources/58-truma-combi-hydronic/Truma-Combi-Service-Handbook_TrumaCorp_20pp.pdf)
- Truma Combi Diagnostics Catalogue (canonical 57-code reference, external PDF at leisureshopdirect.com/pdf/370196265.pdf)
- Truma Combi 4 / 6 / Plus / E / D Technician Service Diagnostic Reference (rv-tech-resources/58-truma-combi-hydronic/Truma_Combi_4_6_Plus_E_D_Technician_Service_Diagnostic_Reference.md)
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