180 Gas valve air/fuel adjustment limit reached

What the control is telling you

The Smart-Sense gas valve has hit its gas-rich or gas-lean adjustment limit, which is restricted by gas type. In normal operation the limits shouldn't be reached.

Applies to: I-Series Plus boilers — 150K BTU and smaller (Combi and Solo)

Likely causes

• Incorrect gas supplied
• Parameter A0 gas type set wrong
• Incorrect gas valve parameters entered
• Flame rod wire disconnected or damaged

Test and repair steps

1. Confirm the correct gas (natural or propane) is being supplied.
2. Check Parameter A0 A = Natural Gas, B = Propane.
3. Check or re-enter the gas valve parameters using 'Enter Gas Valve Values from Integrated Controller' in the Gas Valve Assembly Replacement Instructions (800000253).
4. Confirm the flame rod wire is connected and undamaged.

Models that show this code

4 models in I-Series Plus 150K and smaller

Other codes on the same units

• 120 Flame failure (flame lost during operation)
• 140 Overheat switch tripped (heat exchanger overheating)
• 150 Venturi control fault
• 170 Venturi blockage / position mismatch
• 190 Electrical grounding / short in DC circuit
• 210 Data transfer error
• 220 Gas valve position not detected (reed switch)
• 250 Condensate pump switch tripped (accessory)