ICP ION Furnace Fault Code Reference
Jan 02, 2026
66
List of ION Fault codes. These codes are specifically targeting the Heating/Furnace side. There are other codes for the AC and Heat Pump NOT listed here.
| ICP Code | ION™ Code | Description | MAE | MVE |
| NO CODE | 11 | NO PREVIOUS CODE | Used | Used |
| 2 | 23 | PRESSURE SWITCH DID NOT OPEN | Used | Used |
| LED OFF | 24 | FUSE OPEN | Used | Used |
| 3 | 31 | PRESSURE SWITCH DID NOT CLOSE OR RE-OPENED (LOW/HIGH) | Used | Used |
| 3 | 32 | LOW-HEAT PRESSURE SWITCH DID NOT CLOSE OR RE-OPENED | Used | Used |
| 4 | 33 | LIMIT CIRCUIT FAULT | Used | Used |
| 5 | 22 | ABNORMAL FLAME - PROVING SIGNAL | Used | Used |
| 6 | 34 | IGNITION PROVING FAILURE | Used | Used |
| 7 | 13 | LIMIT CIRCUIT LOCKOUT | Used | Used |
| 8 | 21 | GAS HEATING LOCKOUT | Used | Used |
| 9 | 31 | PRESSURE SWITCH/RELAY DID NOT CLOSE (MED/HIGH/PSR) | Used | Not Used |
| 9 | 31 | HIGH-HEAT PRESSURE SWITCH OR RELAY DID NOT CLOSE/RE-OPENED | Not Used | Used |
| 10 | RAPID FLASH | POLARITY | Used | Used |
| 1+2 | 12 | BLOWER ON AFTER POWER UP | Used | Used |
| 1+5 | 15 | BLOWER MOTOR LOCKOUT | Used | Used |
| 2+5 | 25 | INVALID MODEL SELECTION OR SETUP ERROR | Used | Used |
| 3+5 | 35 | GAS VALVE FAULT | Used | Not Used |
| 4+1 | 41 | BLOWER MOTOR FAULT | Used | Used |
| 4+2 | 42 | INDUCER MOTOR FAULT | Used | Not Used |
| 4+3 | 43 | PRESSURE SWITCH OPEN WHILE HIGHER STAGE SWITCH CLOSED | Used | Used |
| N/A | 45 | CONTROL CIRCUITRY LOCKOUT | Used | Used |
| 6+1 | 14 | IGNITION LOCKOUT | Used | Used |
