Vokera AL55 Fault Code: Causes, Fixes & Repair Costs
What does the Vokera AL55 fault code mean?
The AL55 code indicates that the boiler's control board has detected a problem with the configuration jumper tag — a small physical electrical connector fitted to the PCB that tells the board what type and specification of boiler it is controlling. Without a reliable signal from this tag, the PCB cannot confirm it is set up correctly and will lock the boiler out as a precaution. When the fault first appears it flashes on the display; once the boiler enters full lockout the red LED illuminates and the pump runs a 60-second post-circulation cycle before shutting down. This fault is not related to gas, water pressure, or heat — it is purely an electrical configuration issue on the circuit board.
General guidance only — not a substitute for professional advice, and not certified by a Gas Safe engineer. Always have your specific appliance assessed by a qualified professional. 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
- Dislodged or missing jumper tag Common
The jumper tag is a small clip-on connector that can work loose over time, particularly after a service visit where the boiler casing has been removed and refitted. If it has fallen off or been accidentally displaced, the PCB immediately loses its configuration signal and triggers AL55.
- Poor or corroded electrical connection Sometimes
Even when the jumper tag is physically present, a build-up of corrosion or a slightly loose seating on the connector pins can interrupt the signal. This is more likely on older boilers or those installed in damp environments such as utility rooms or outbuildings.
- Incorrectly positioned jumper tag Sometimes
If the boiler has been worked on previously and the tag was refitted in the wrong position on the PCB header, the board will read an unrecognised configuration and flag a fault. This is usually the result of a previous repair rather than a spontaneous failure.
- Faulty PCB Rare
In a minority of cases the PCB itself has developed an internal fault — either a failed component near the jumper tag circuit or broader board degradation — that causes it to misread or fail to detect the tag even when it is correctly fitted and in good condition.
How to fix it
- Reset the boiler DIY safe
Turn the mode selector to the Off/Reset position, wait approximately 10 seconds, then switch it back to your normal heating or hot water setting. If the boiler restarts and runs without the code returning, monitor it over the next hour or two. A one-off reset is reasonable; do not repeat more than two or three times, and do not reset repeatedly if the code keeps coming back immediately.
- Check for any obvious recent work on the boiler DIY safe
Think back to whether the boiler was serviced or repaired recently. If an engineer visited in the last few days or weeks and opened the casing, the jumper tag may have been accidentally dislodged when the panels were removed or refitted. Pass this information on when you call for help — it will save diagnosis time.
- Contact a Gas Safe registered engineer to inspect the PCB and jumper tag Gas Safe engineer
An engineer will open the boiler casing, locate the jumper tag on the PCB, and confirm it is present, correctly positioned on the right set of pins, and making a clean electrical connection. If the tag is loose or corroded, reseating or replacing it is typically a quick, low-cost fix. If the PCB itself has failed, the board will need to be replaced — a more involved repair but still straightforward for a competent engineer familiar with Vokera products.
Parts you may need
- PCB configuration jumper tag / connector · from £15
- Vokera PCB (control board) · from £220
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 £90–£320, depending on the underlying cause.
Frequently asked questions
Can I fix the AL55 fault myself by reseating the jumper tag?
It is understandable to be tempted, especially if you can see the jumper tag on the circuit board. However, working inside the boiler on the PCB is not a DIY task — not because it involves gas directly, but because incorrect handling of the board can cause further electrical damage or invalidate any remaining warranty. A Gas Safe engineer will be able to inspect and reseat or replace the tag safely, and the labour time involved is usually short, keeping costs reasonable.
How much does it cost to fix a Vokera AL55 fault?
If the fix is simply reseating or replacing the jumper tag connector, the total cost including the engineer's call-out and labour is typically in the region of £90–£150. If the PCB itself has failed and needs to be replaced, expect to pay roughly £220–£320 for parts and labour combined. In rare cases where a premium or hard-to-source board is needed, costs can edge higher — but for most Vokera models the board is a standard item. Vokera also offers a fixed-price repair service (call 0344 391 0999) which may be worth comparing.
Is AL55 a dangerous fault?
No — AL55 is a configuration fault, not a safety-critical issue involving gas, combustion, or carbon monoxide. The boiler has locked out as a precaution because it cannot confirm its own setup, not because there is an active hazard. That said, you should not attempt to bypass the lockout, and the boiler should be left off until an engineer has identified and resolved the root cause.
My Vokera keeps showing AL55 after a recent service — why?
This is a common scenario. When an engineer services the boiler they remove the casing and may inadvertently dislodge the small jumper tag connector from the PCB during the process. Contact the engineer who carried out the service and explain what has happened — in most cases they will return to reseat it, and if the work was done recently this should be covered without an additional call-out charge.