Display shows sensor short-circuit error, temperature reading extremely high

Safety first: Disconnect power before testing sensors.

Step-by-step checks:

• Identify which sensor: Use the diagnostic menu or manual to determine whether the DHW, flow, return, or flue sensor is implicated.
• Inspect wiring: Look for crushed or pinched cables, especially where they pass through metal panels.
• Dry connectors: If there is condensation, gently dry the connectors and surrounding area.

When to call a professional: Sensor resistance testing and replacement should be done by a technician if you are not experienced with electrical measurements.