Outdoor unit high pressure system error
The P04 error code on Toshiba boilers indicates outdoor unit high pressure system error.
Toshiba P04 means: outdoor unit high pressure system error. The usual cause is an error detected in the high pressure control via the te sensor. You can safely reset the boiler once — if P04 returns, do not keep resetting. A qualified heating engineer should diagnose the root cause.
What Does P04 Mean
The P04 code is shown by the boiler’s control board when it detects outdoor unit high pressure system error. The boiler then stops instead of continuing to run in that condition: the code is the appliance reporting a problem, not proof that the boiler is broken.
| What you see on the boiler |
|---|
| The display shows P04 and the boiler stops until the fault is cleared |
Common Causes
Causes documented in the Toshiba service literature published by centriassistenza.org, cross-checked against the manufacturer’s fault-code table.
| Cause |
|---|
| An error detected in the high pressure control via the TE sensor |
Safety Warning
P04 involves electrical or pressure-related components. Do not attempt repairs without proper qualifications. Ensure the boiler is electrically isolated before any inspection. If you notice water leaks, unusual sounds, or pressure anomalies, contact a qualified heating engineer immediately.
Parts & Prices
Prices shown are indicative. Actual prices and availability vary by region.
Step-by-Step Diagnosis
1. Note the exact error code and check the manufacturer's installation and service manual for specific guidance. 2. Check all visible wiring connections for security and condition. 3. Power cycle the boiler — switch off at the mains for 30 seconds, then switch back on. 4. If the fault recurs, check the fault history for related or recurring codes. 5. Inspect the boiler for any obvious signs of damage, leaks, or unusual sounds
How to Fix It
Have this checked: An error detected in the high pressure control via the TE sensor
Refer to the Toshiba service documentation for the detailed procedure. Only a qualified engineer should carry out these repairs.
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Affected Models
Toshiba models that can display fault code P04:
| Model Family | Output Range | Frequency |
|---|---|---|
| All Toshiba models | — | Possible |
Frequently Asked Questions
P04 is not classified as a high-severity fault, so the boiler can be reset once. If P04 comes back, stop resetting: the underlying cause is still there and needs a qualified heating engineer.