FieldBench
ICP codes

ICP

31

Lockout

Draft / pressure switch

Inducer running, the one PS did not close (or the draft path will not hold). On this 96% that is trap / PVC / inducer.

Walk 31 in Diagnose

3 plates — walk the one on the cabinet

First check

1 Prove inducer and the live code

Do not pull power — that clears the ICP N80ESN active code. Write 31. Is the inducer spinning on this call? Silent inducer is not a pressure switch. This is Category I metal vent. There is no 96% collector or PVC trap to prime.

Expect: 120 VAC at the inducer on a heat call. Wheel turning.

If fail: 120 VAC missing → IFC / door switch / incoming power. Voltage + dead motor → inducer.

If pass: Inducer running + this code → trap, hose, switch, vent (step 2).

The rest of the walkthrough is Diagnose.

On the plates

  • One PS only — do not hunt a second high-fire switch.
  • Dump the trap and open the collector. N9MSB 96% drowns overnight.
  • PVC intake/exhaust, ice, wind, hose on the only collector tap.
  • Inducer 120 VAC and spinning. This is not Goodman 3-flash even if the neighbor unit is.
  • This is Category I metal vent. There is no 96% collector or PVC trap to prime.
  • Cap, liner, common-vent tables, inducer wheel, hose on the inducer housing.

Plates that use 31

Same number, other makers

31 on ICP is not the same code on these plates.