Hold / Lockout 67 ILK off - interlock string open

What the control is telling you

The interlock chain that must be closed before the burner can run is open. On this boiler the string includes the built-in low water cutoff and any external limit wired to LIM. Display typically reads Lockout 67 ILK OFF.

Applies to: Trinity Tft60, Tft85, Tft110, Tft154, Tft201, Tft285, Tft340, Tft399

Likely causes

• Low water condition (internal low water cutoff open)
• External limit wired to LIM is open
• Condensate blockage switch opened (water backing up or exhaust restricted)

Test and repair steps

1. Check the internal low water cutoff operation and system water level
2. Check the external limit between R and LIM; if it is open the fault is in that device, not the boiler
3. Clean the condensate trap and drain, then check the vent for blockage and clear the lockout
4. If drain and vent are clear, take the vinyl tube off the condensate switch and check contacts 1 and 2 for continuity; replace the switch if open

Models that show this code

13 models in Trinity Tft

Other codes on the same units

• Hold / Lockout 156 Combustion pressure and Flame ON
• Hold / Lockout 240 Invalid Outdoor connector type setting
• Hold / Lockout 243 Invalid UV with spark interference not compatible with Igniter on throughout
• Hold / Lockout 67 ILK off - interlock string open
• Hold / Lockout 79 Outlet high limit
• Hold / Lockout 79 Outlet high limit
• Hold / Lockout 81 Delta T limit
• Hold / Lockout 81 Delta T limit