York Gas Furnaces
Most York gas furnaces have a control board inside the furnace blower compartment that will flash a diagnostic code that shows the operating status of the furnace.
| Diagnostic Codes: | ||
| Slow Green | Normal Operation – no call for heat | |
| Slow Amber | Normal Operation – with a call for heat | |
| Steady On Red | Control failure | Replace control board (S9200U is a suitable replacement) |
| Rapid Red | Twinning error, incorrect 24V phasing | Try switching polarity at transformer. |
| Rapid Amber | Low flame sense current | Clean flame sensor |
| 4 Amber | Y present without G | Low voltage wiring problem |
| 1 Red | Flame present with gas off | Stuck gas valveShorted flame sensor Faulty control |
| 2 Red | Pressure switch stuck closed | Bad pressure switchInducer fan relay stuck on |
| 3 Red | Pressure switch stuck open | Bad pressure switchBad inducer fanBad inducer fan relayBlocked or restricted ventCondensate drainage issue |
| 4 Red | Limit switch open / open fuse | Bad limitLow airflowOver-Fired |
| 5 Red | Rollout switch open / open fuse | Bad switchCracked heat exchangerBad inducer motorOver-Fired |
| 6 Red | Pressure switch opened 4 times | Bad pressure switchBad inducer fanBlocked or restricted ventCondensate drain issue |
| 7 Red | Ignition lockout due to 3 retries | Bad igniterDirty flame sensorNo gas flow |
| 8 Red | Flame signal lost 5 times | Dirty flame sensorCombustion air problem |
| 9 Red | Grounding or line polarity fault | Try reversing transformer power |
| 10 Red | Flame sensed with no call for heat | Stuck gas valveShorted flame sensor Faulty control |
| 11 Red | Extended limit switch open | Bad limitBlower failure |
| 12 Red | Open igniter circuit | Bad igniterLoose wiring to igniter |
| 13 Red | 2nd Stage Pressure switch stuck open | Bad pressure switchBad inducer fanBlocked or restricted ventCondensate drain issue |
Lockout Codes
Fault Code Retrieval: With no thermostat call push and release the LAST ERROR button. The LED will flash up to 5 stored fault codes, beginning with the most recent. If there are no codes in memory, the LED will flash two green flashes.
Clear the Fault Codes: Push and hold the LAST ERROR button for at least five seconds. The LED will flash three green flashes when the memory has been cleared.
