The PCB is the control centre of the Baxi combi boiler. Baxi 600, 800, and Platinum PCBs manage the complete ignition sequence, gas valve modulation, pump control, fan speed, and all safety interlock functions. When a Baxi PCB fails, the boiler typically presents with fault code E168 or simply fails to respond.
E168 — The Baxi PCB Fault Code
E168 is Baxi’s most direct PCB fault indicator. Unlike ignition or pressure fault codes that can have multiple component causes, E168 on a Baxi combi typically indicates an internal PCB fault.
When E168 appears:
- Attempt a reset — hold the reset button for 3 seconds. If E168 returns immediately, the PCB is not recovering.
- Confirm the electrical supply to the boiler is clean — voltage spikes can damage PCBs.
- Check the wiring harness for damage, corrosion, or loose connectors.
- If all checks pass and E168 persists: PCB replacement is required.
Baxi PCB Variants by Model
Baxi PCBs are not interchangeable between the 600 series, 800 series, and Platinum range. Always confirm the full model number and serial number when ordering.
Baxi 600 series PCBs: Stocked for 618, 624, and 628 Combi variants. Baxi 800 series PCBs: Stocked for 800 Combi 24, 28, and 33 variants. Baxi Platinum PCBs: Stocked for Platinum Combi 24HE, 28HE, and 33HE. Note: Potterton Promax PCBs share architecture with Baxi Platinum. Baxi EcoBlue PCBs: Current range, stocked for main output variants.
Preventing Future PCB Failure
PCBs can fail due to:
- Damp/condensate ingress: Ensure the condensate pipe is correctly installed and free of blockages.
- Voltage spikes: A boiler surge protector (fitted at the fused spur) reduces this risk.
- Age and thermal cycling: PCBs in boilers more than 10 years old are at higher risk.
Installation Notes
Baxi PCB replacement is a Gas Safe engineer task. After fitting a new Baxi PCB:
- Power up and check for fault codes before attempting ignition
- Test all operational modes (CH mode, DHW mode if combi)
- Confirm safety cutouts operate correctly
- Run the boiler through 2–3 complete cycles and check for fault recurrence
Need a Recommended Installer?
- HGB Heating Kent — Gas Safe engineers, Baxi specialists, Kent and Medway
- Boiler Sense — Certified boiler specialists, Kent and South East London