PCB lock out – may follow a power supply problem, try resetting
The E168 error code on Baxi boilers indicates pcb lock out – may follow a power supply problem, try resetting.
Baxi E168 means: pcb lock out – may follow a power supply problem, try resetting. On this component the documented failure modes are mains electrical supply low or unstable. You can safely reset the boiler once — if E168 returns, do not keep resetting. A qualified heating engineer should diagnose the root cause.
What Does E168 Mean
The E168 code is shown by the boiler’s control board when it detects pcb lock out – may follow a power supply problem, try resetting. 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 E168 and the boiler stops until the fault is cleared |
Common Causes
The manufacturer does not publish a cause list for this specific code. The causes below are the failure modes documented for the same component on other boilers, confirmed by the service literature of 8 different manufacturers.
| Cause |
|---|
| Mains electrical supply low or unstable |
Safety Warning
E168 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. Check for visible damage on the PCB — look for burnt components, corrosion, or water marks. 2. Check all wiring connections to the PCB are secure. 3. Try a power cycle — switch the boiler off at the mains for 30 seconds, then switch back on. 4. If the fault persists after power cycling, check the error code history for related faults. 5. Verify the mains voltage supply to the PCB is stable (230V ±10%). 6. Check the earth connection
How to Fix It
Measure the mains voltage at the boiler; if it is low or unstable the fault is in the property’s electrical supply, not the boiler.
Refer to the Baxi service documentation for the detailed procedure. Only a qualified engineer should carry out these repairs.
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Affected Models
Baxi models that can display fault code E168:
| Model Family | Output Range | Frequency |
|---|---|---|
| All Baxi models | — | Possible |
Frequently Asked Questions
Measure the mains voltage at the boiler; if it is low or unstable the fault is in the property’s electrical supply, not the boiler. According to the technical documentation, this is the first check on the list for E168.
E168 is not classified as a high-severity fault, so the boiler can be reset once. If E168 comes back, stop resetting: the underlying cause is still there and needs a qualified heating engineer.