!
error HP

Error Code Red LED 1 blink every second followed by a 2 second pause

CPU thermal shutdown detected.

? What Causes This

High temperature that exceeds the cooling system capacity.

How to Fix It

  1. Verify and clean fans, ventilation area around the unit.
  2. Check CPU fan operation and reseat if necessary.
  3. If issue persists, contact service personnel.

Source: page 3 of the official manual

From the manual

Manual page 3 — HP error Red LED 1 blink every second followed by a 2 second pause

This error code appears in:

HP Elitedesk 800 G1 Small Form Factor PC