York Steady On

What does York Steady On mean?

A continuously lit (steady on) ignition control LED indicates the board's microprocessor has not passed its internal self-check. The control holds its output relay contacts open so the inducer and gas valve cannot operate. York's table notes this can be triggered by a transient electrical event, so the first step is to cycle power; if the steady-on indication returns, the board has failed and must be replaced.

Symptoms

• Ignition control LED stays continuously lit instead of flashing
• No heat; inducer and gas valve are inhibited
• Condition may clear after a power cycle, or may repeat
• Furnace will not begin an ignition sequence

Common causes

• Microprocessor failed its power-on self-check
• Transient voltage event such as a surge or brownout
• Excessive voltage applied to the control
• RF interference disrupting the microprocessor

Diagnostic steps

1. 01

   Cycle power to the control

   Remove and restore 24 VAC power to rule out a transient condition that created a false self-check failure.

2. 02

   Wait for the watchdog timer

   The control may also recover after its 60-minute watchdog timer expires; observe whether normal operation returns.

3. 03

   Investigate the supply quality

   If the indication repeats, check for excessive voltage, surges, brownouts, or RF interference that could disrupt the microprocessor.

4. 04

   Replace the control if it repeats

   If the steady-on LED returns after power cycling and the supply is verified clean, replace the ignition control board.

When to call a professional

If a single power cycle clears the steady-on LED and heat resumes, the event was likely transient and no further service is needed. If the indication repeats, a licensed HVAC technician should verify the supply voltage and electrical environment before condemning the board, then replace the failed control. Persistent self-check failures can also point to upstream power-quality problems that need professional measurement to resolve.