05 01 Ignition lockout after 3 failed attempts

What the control is telling you

The boiler locks out after the 3rd consecutive failed ignition attempt. It is also used to test the ignition circuit during first start-up.

Applies to: TRX150 and related TRX models

Likely causes

• Gas supply not open or gas pressure too low
• Gas leak at a connection
• Ignition device or flame sensing problem
• Post-purge too short before the igniter is reactivated

Test and repair steps

1. Confirm the gas valve is open and gas pressure is present at the inlet.
2. Check all gas connection seals, including the boiler connection, and eliminate any leak.
3. Make sure the combustion fan post-purges for at least 5 seconds before the igniter reactivates.
4. Set the room thermostat back to normal after the error appears.
5. Press RESET to clear Error 501. The display should show OK.
6. Restart the boiler by selecting CH or DHW.

Models that show this code

5 models in TRX

Other codes on the same units

• 4 12 Room sensor open or short circuit, Zone 2
• 4 13 Room sensor open or short circuit, Zone 3
• 4 30 Detected accessory wired to BUS connection
• 4 31 Code 431 (no description printed)
• 05 02 Flame detected with gas valve closed
• 05 04 10 flame lifts in one operating cycle
• 5 P1 1st ignition failed
• 5 P2 2nd ignition failed