Baxi E.02-.16 Fault Code: Causes, Fixes & Repair Costs
What does the Baxi E.02-.16 fault code mean?
The E.02-.16 code is a permanent lockout fault on Baxi boilers, triggered when the on-board Channel Service Unit (CSU) — an embedded communications controller within the printed circuit board (PCB) — fails to complete its internal handshake within the expected time window. Because the boiler classifies this as a permanent fault rather than a temporary error, it will not attempt to restart automatically. An engineer must attend, diagnose the underlying cause, and manually reset or repair the unit before heating or hot water can be restored. In practice this fault almost always points to either a CSU communication failure or physical damage to the PCB itself.
General guidance only — not a substitute for professional advice. Any gas work must be carried out by a Gas Safe registered engineer. If you smell gas or suspect carbon monoxide, leave the property and call the National Gas Emergency line on 0800 111 999.
Common causes
- CSU Communication Time-Out Common
The Channel Service Unit embedded on the PCB failed to complete its internal communication cycle within the required period. This can be triggered by a brief power surge, electrical noise on the supply, or a firmware glitch — but if the boiler locks out permanently and the fault returns after an engineer reset, it usually indicates the CSU component itself has degraded and the PCB needs closer inspection.
- PCB Component Damage or Failure Common
The PCB may show signs of burning, corrosion, or failed surface-mount components. Damage can result from moisture ingress, prolonged overheating (often caused by a restricted flue or poor ventilation around the boiler), or simply age-related wear on electronic components. A damaged PCB will cause the CSU to behave erratically, triggering this exact lockout.
- Electrical Supply Issues or Power Surge Sometimes
A sudden spike or dip in the mains supply can corrupt the CSU's internal process mid-cycle, causing a one-off time-out. If the fault clears after an engineer reset and does not recur, a transient electrical event is the likely culprit rather than a hardware failure. Fitting a surge-protected spur is worth considering in areas prone to power fluctuations.
- Loose or Corroded Internal Wiring Sometimes
Poor connections between the PCB and other boiler components can introduce electrical noise that disrupts CSU communication. Harness connectors can loosen over years of thermal cycling, and corrosion on pins in damp boiler cupboards can cause intermittent signal loss sufficient to trigger the time-out.
How to fix it
- Do not attempt to open the boiler casing or touch any internal components DIY safe
This is a permanent electronics-level lockout. Unlike pressure or condensate faults, there is no homeowner-level check that will resolve E.02-.16. Opening the casing or probing the PCB yourself risks electric shock, could void any remaining warranty, and is unlikely to fix the underlying fault.
- Try a single manual reset DIY safe
Press and hold the reset button on your Baxi boiler for around 3 seconds, then release and wait 2–3 minutes. If the boiler fires up and runs normally, monitor it closely over the next 24 hours. If the fault returns — which is common with a true CSU failure — do not keep resetting repeatedly, as this will not fix the root cause and may mask useful diagnostic information for the engineer.
- Check that your mains gas supply is on DIY safe
Confirm other gas appliances in your home (hob, fire) are working normally. If they are not, contact your gas supplier before calling a boiler engineer. A complete loss of gas supply would prevent the boiler from running regardless of the electronics fault.
- Note any recent events before calling an engineer DIY safe
Think back to whether there was a power cut, storm, or thunderstorm shortly before the fault appeared. This information helps the engineer distinguish a one-off transient event from a developing hardware failure, potentially saving diagnostic time and cost.
- Call a Gas Safe registered engineer for diagnosis and repair Gas Safe engineer
A qualified engineer will inspect the PCB for visible damage such as scorch marks, corrosion, or blown components, and check the wiring harness connections. If the CSU or PCB is confirmed faulty, the board will need to be repaired by a specialist electronics repairer or replaced entirely. It is essential that any replacement PCB is the correct part number for your specific Baxi model — an incompatible board can cause further damage or a complete system failure. Your engineer may also check whether the root cause (e.g. overheating from a restricted flue) needs addressing at the same time.
Parts you may need
- Baxi PCB (model-specific — confirm part number before ordering) · from £230
- Wiring harness / internal loom · from £45
- Surge-protected fused spur (preventative) · from £20
The exact spare depends on your boiler's GC number (on the data badge). Check this against the part before buying.
Typical repair cost
Expect to pay roughly £280–£480, depending on the underlying cause.
Frequently asked questions
Can I reset a Baxi E.02-.16 fault myself?
You can try a single manual reset — press and hold the reset button for about 3 seconds. If the boiler starts and the fault does not return, a transient electrical event may have caused a one-off CSU time-out. However, because E.02-.16 is classified as a permanent lockout, it will not clear itself and is very likely to return if there is an underlying PCB or CSU fault. Repeatedly resetting the boiler will not fix the hardware and is not recommended. An engineer visit is almost always needed.
How much does it cost to fix a Baxi E.02-.16 fault?
Most homeowners pay somewhere between £280 and £480 for a PCB inspection and replacement, including parts and labour. The PCB itself typically costs around £200–£300 depending on the Baxi model, and labour for an experienced engineer usually adds £80–£150. If the fault turns out to be a loose wiring connection rather than a failed PCB, the cost can be considerably lower. On older boilers (10 years or more), it is worth getting a quote for a new boiler alongside the repair cost, as a PCB replacement on an ageing appliance may not represent good value.
Why does Baxi use the term 'permanent fault' for E.02-.16?
Baxi categorises faults as either 'resettable' (the boiler can attempt a restart automatically or after a simple user reset) or 'permanent' (the boiler locks out completely and requires manual engineer intervention to clear). E.02-.16 falls into the permanent category because a CSU time-out indicates an electronics-level failure that the boiler's own control logic cannot safely recover from. This is a deliberate safety design — the boiler stays locked out until a qualified person has confirmed it is safe to run again.
Is it worth repairing a PCB on an older Baxi boiler?
It depends on the age and overall condition of the boiler. Baxi boilers typically have a useful service life of 10–15 years. If yours is under 8 years old and otherwise in good condition, a PCB repair or replacement is usually worthwhile. On boilers older than 10–12 years, it is sensible to weigh the repair cost against the likely remaining lifespan — especially if other major components (pump, heat exchanger, fan) are also showing signs of wear. Ask your engineer for an honest assessment before committing to the repair.