My PM5 is displaying error code 4

Symptom:

One or more of the buttons on the monitor are unresponsive when being pressed and error code 4 is displayed.  

Resolution:

This error code can occur if a button is stuck in the engaged position when the monitor resets or powers on. 

1. Look for a button that is stuck in a pressed position. Try pressing or moving the button to release it. 
2. If the issue happens after changing the batteries, take out the batteries and put them back in carefully, ensuring no buttons are being pressed during the process. 
3. If the monitor is no longer under warranty and the error persists, there might be residue behind the keypad. Use isopropyl alcohol to clean it. Follow the initial steps in the  PM5 Monitor LCD Replacement (PDF) guide to access and clean the button contacts on the circuit board. Check for any corrosion on the circuit board.  

If you have completed steps 1-3 and the error message persists, you will need to replace the PM5 monitor.