Verified boiler fault code
ATAG 1P4 Fault Code (i-Range (2019 and newer))
Pressure below Pmin (0.5–0.8 bar); filling is needed.
Safety disclaimer
Fault code summary
- Manufacturer
- ATAG
- Fault code
- 1P4
- Fault type
- Low pressure, Pressure sensor
- Severity
- blocking
- Reset
- ATAG's troubleshooting guidance says the system should be around 1.0–1.1 bar cold and directs users to the manual or installer for filling.
- Applicable models
- ATAG iC, ATAG iS, ATAG iR
Quick answer
Pressure below Pmin (0.5–0.8 bar); filling is needed.
What does this fault code mean?
Pressure below Pmin (0.5–0.8 bar); filling is needed.
Common causes
- System pressure between 0.5 and 0.8 bar.
Symptoms
- The ATAG display shows code 1P4 and the pressure gauge may be below the recommended cold pressure.
What can the homeowner safely check?
- Read the pressure gauge/display and use a filling loop only as described by the user manual.
Boiler reset information
ATAG's troubleshooting guidance says the system should be around 1.0–1.1 bar cold and directs users to the manual or installer for filling.
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
- Check pressure, leaks, pressure sensing and filling arrangement.
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: 1P4 — Pressure < Pmin (0.5 < 0.8 bar), Filling needed.
Last verified
2026-09-12
Frequently asked questions
What does ATAG 1P4 mean?
Pressure below Pmin (0.5–0.8 bar); filling is needed.
Can I reset a ATAG 1P4 fault?
ATAG's troubleshooting guidance says the system should be around 1.0–1.1 bar cold and directs users to the manual or installer for filling.