NTI · Boiler

Lockout 173 Pilot relay feedback incorrect

Critical severity Trinity Tft

What the control is telling you

Control board pilot relay feedback does not match what the control commanded.

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

Likely causes

Failing limit switch in the ILK circuit
Control board hardware failure

Test and repair steps

Check the internal low water cutoff and any external limit between R and LIM; replace if faulty
Reset power; replace the control if the code returns

Models that show this code

13 models in Trinity Tft

Tft110Tft154Tft155Tft175Tft200Tft201Tft250Tft285Tft300Tft340Tft399Tft60Tft85

Other codes on the same units

Lockout 171 Safety relay feedback incorrect in run
Lockout 172 Main relay feedback incorrect
Lockout 172 Main relay feedback incorrect
Lockout 173 Pilot relay feedback incorrect
Lockout 174 Safety relay feedback incorrect
Lockout 174 Safety relay feedback incorrect
Lockout 175 Safety relay open
Lockout 175 Safety relay open

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Source: NTI Trinity Tft399 Installation and Operation Manual (2018-09-07), Sec. 16.0 Troubleshooting, Table 16-3. Summarized in our own words; check the original manual for your model.

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For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.