Overview
This error means the burner control unit fitted in the boiler is not recognised as compatible with the KIM (boiler identification module) or the boiler’s control electronics. In plain terms the control modules that talk to each other inside the GB162 are mismatched — either the wrong replacement part was fitted, a code plug / identification link is missing or faulty, or the new module has incompatible firmware. Because the boiler uses matched modules to manage ignition, gas control and safety interlocks, a compatibility fault will usually prevent normal operation. Severity: this is a locking fault that will typically stop the boiler from firing for safety reasons. It is not a simple sensor or pressure issue; it relates to key control electronics. While some basic checks and a controlled reset can be tried by a homeowner, diagnosing and repairing a module mismatch, fitting the correct replacement module or reprogramming is work for a qualified Gas Safe engineer or Worcester Bosch service technician. Do not attempt to alter gas or mains-connected control electronics yourself.
Possible Cause: The burner control unit that has been fitted is not compatible with the KIM (boiler identification module).
Troubleshooting Steps
Safety first
- If you smell gas, get everyone out of the property and call the gas emergency number immediately. Do not operate electrical switches or the boiler. Call a Gas Safe engineer.
- Otherwise isolate electrical power to the boiler only if you are comfortable doing so; do not attempt to remove or replace gas-carrying components or internal electronics unless you are a qualified engineer.
Initial homeowner checks (safe, low-risk)
1. Note the exact fault code display and any accompanying three-digit cause code shown in the information menu or when the spanner/return button is pressed. Record it and take a photo of the display.
2. Try a controlled reset: follow the boiler manual — press the reset button for about 5 seconds and allow the boiler to attempt a restart. If the code clears and the boiler operates normally, monitor for reoccurrence. If it returns, stop attempting further resets and call a professional.
3. Check whether any recent service, repair or part replacement was carried out (for example a control board, HCM, burner control or code plug). If a part was recently fitted, note the installer and the part number if available.
4. Visual inspection from the outside: with the boiler isolated from mains power, remove the outer cover only if you are comfortable and confident. Do not touch wiring or components. Look for an obvious loose cable, disconnected code plug or damaged connector. Take clear photos of the module area and any labels/part numbers but do not probe or disconnect components.
Specific diagnostic and next-step actions (for the engineer / to prepare for the engineer)
1. Compatibility check: the technician will compare the part numbers and firmware versions of the burner control unit (BC/HCM/UBA/KIM) to the boiler type. 9A 361 indicates a mismatch between the burner control and the KIM; one of those parts will need to be the correct, matched version for the GB162.
2. Code plug / identification module: the engineer will check the presence and seating of the code plug/KIM and verify it is the correct item for your boiler. If the code plug is missing, incorrectly fitted or damaged it will trigger compatibility errors.
3. Connector and wiring check: inspect plug connections for bent pins, corrosion or a poor connection between the UBA/BC10/KIM modules. Loose or poor connections can cause communication errors that look like incompatibility.
4. Replace or re-fit parts as required: the permanent fix is to fit the correct, compatible burner control or KIM (or both) and, where required, install the correct code plug or reprogramme the UBA by a qualified engineer. Do not attempt to fit or replace control modules yourself — these are mains- and gas-connected components and must be handled by a Gas Safe registered engineer.
5. After repair the engineer will reset the boiler and confirm normal operation, and may run diagnostic tests and record the cause code and remedial work.
Who to call and what to prepare
- Contact your original installer or a Gas Safe registered engineer. If the boiler is under warranty contact Worcester Bosch support (technical support numbers are provided in the manual) and arrange an authorised service visit. Have the boiler model, serial number, error code (9A 361) and any photographs or part numbers ready.
- Do not continue to cycle the boiler on and off repeatedly if the fault persists; note the fault and wait for a qualified engineer.
Final notes
- This is not a routine DIY repair. The fault concerns core control modules that manage ignition and safety and will usually require a matched replacement part or professional reconfiguration. A qualified engineer should complete the diagnosis and fit the correct hardware or reprogramme the control modules to restore safe operation.
Helpful Resources
Boiler Manual
Download the official PDF manual for the Worcester Bosch GB162 Boiler.