Bosch Coding Plug / Parameter Module Fault

Boiler indicates a coding plug or parameter module fault; may not operate.

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Missing or incorrect coding plug, Poor contact on coding plug connector, Faulty parameter module, PCB not reading coding plug

Safety: Isolate power before accessing the control compartment.

Steps:

Locate the coding plug or parameter module on the control board (refer to Bosch manual).
Ensure it is fully inserted and not damaged.
If recently replaced, verify that the correct coding plug for your boiler model has been installed.

If the plug is correct and properly seated but the fault persists, the PCB or plug may need replacement by a Bosch service engineer.

Hard 4/5

Coding Plug / Parameter Module

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