An error code is useful evidence—not a complete diagnosis. Here is how to prepare the right information.
Short answer
An error code indicates that the system has detected a condition that needs attention. Record the code exactly, take a photo if safe to do so and note when it appeared. The code helps direct diagnostics, but it does not confirm the underlying cause on its own.
Record the message exactly
Write down the full code, letters and numbers shown on the controller. A photograph can be useful, provided it is safe and does not require opening equipment or accessing electrical components.
Add the context around it
Note whether the code appeared during heating, hot-water demand, a change in weather or after a power interruption. Also record whether the message is permanent, intermittent or clears after a normal controller action.
Use the code to guide, not replace, diagnostics
Manufacturer documentation and system configuration affect what a code means. A diagnostic visit uses the code alongside the system’s operation and reported history to establish the appropriate next step.
You may find model-specific information, but online results do not confirm the cause for your installation. Use the code as useful information when arranging a professional assessment.
What details should I include with a heat pump error code?+
Include the exact code, heat pump make and model if known, when the message started and what the system was doing when it appeared.