Verified boiler fault code
ATAG 203 Fault Code (i-Range (2019 and newer))
Tank probe damaged (solo).
Safety disclaimer
Fault code summary
- Manufacturer
- ATAG
- Fault code
- 203
- Fault type
- Temperature sensor, Hot water
- Severity
- Not specified
- Reset
- ATAG distinguishes blocking codes from error codes; a locked boiler may require reset and/or service intervention.
- Applicable models
- ATAG iS
Quick answer
Tank probe damaged (solo).
What does this fault code mean?
Tank probe damaged (solo).
Common causes
- Tank probe damaged.
Symptoms
- The ATAG display shows error code 203.
What can the homeowner safely check?
- Record the code and contact the installer.
Boiler reset information
ATAG distinguishes blocking codes from error codes; a locked boiler may require reset and/or service intervention.
When should I call an engineer?
Contact a suitably qualified heating engineer when the fault persists, the boiler locks out, or the manufacturer instructions do not resolve it. For gas appliance work in the UK, use a Gas Safe registered engineer.
Engineer diagnosis
- Test the tank probe and its wiring.
Applicable boiler models
Related fault codes
- 101 — i-Range (2019 and newer)
Overheat.
Read fault code - 102 — i-Range (2019 and newer)
Pressure sensor error.
Read fault code - 103 — i-Range (2019 and newer)
Flow check failed three times (flow-check sequence 1, 3 or 4; last check 1).
Read fault code - 104 — i-Range (2019 and newer)
Flow check failed.
Read fault code - 105 — i-Range (2019 and newer)
Flow check failed three times (flow-check sequence 1, 3 or 4; last check 3).
Read fault code - 106 — i-Range (2019 and newer)
Flow check failed three times (flow-check sequence 1, 3 or 4; last check 4).
Read fault code - 107 — i-Range (2019 and newer)
Flow check 5 failed.
Read fault code - 108 — i-Range (2019 and newer)
Pressure below Pmin (less than 0.5 bar); filling is needed.
Read fault code
Manufacturer documentation
ATAG - Boiler Troubleshooting2019 & newer range: 203 — Tank Probe Damaged (Solo).
Last verified
2026-09-12
Frequently asked questions
What does ATAG 203 mean?
Tank probe damaged (solo).
Can I reset a ATAG 203 fault?
ATAG distinguishes blocking codes from error codes; a locked boiler may require reset and/or service intervention.