Boiler displays E08; unit may not start or may shut down intermittently.

Safety: Turn off power before working on wiring.

• Locate outdoor sensor: The IBC outdoor sensor is typically mounted on an exterior north or northwest wall, away from direct sun. Inspect the sensor housing for damage.
• Check wiring: Follow the low-voltage cable back to the boiler. Ensure connections at the sensor and at the boiler's outdoor sensor terminals are tight and polarity is correct if specified.
• Inspect cable: Look for cuts, staples through the cable, or water ingress at junctions.
• Bypass test (if allowed by manual): Some IBC controls allow disabling outdoor reset in the menu. Temporarily disable it to see if the boiler operates normally without the sensor.

If E08 persists, replace the outdoor temperature sensor with the correct IBC part. If a new sensor does not clear the error, the control board input may be faulty and should be checked by a technician.