Ignition failure occurs when the burner completes the pre-purge but no flame is created or confirmed within the allowable safety time. Diagnosis must distinguish whether the spark, the ignition gas, or the flame verification is missing.
Spark check
It is checked whether the ignition transformer is powered, whether the high-voltage cable is in good condition, and whether the electrode is positioned correctly with the gap as specified by the manufacturer.
Pilot burner
In systems with a pilot, it is checked whether the pilot valve opens, whether there is sufficient gas pressure, and whether the small flame is created at the correct point.
Main valves
If there is a pilot but the main flame does not ignite, the opening sequence of the main valves, the gas pressure, and their actual position are checked.
Safety time
If the flame is created but its verification is delayed, the BMS may lead to a lockout. The problem may lie with the sensor and not the ignition itself.
Practical diagnosis
The exact step where the sequence stops is recorded: spark, pilot, main gas, or flame proving. This avoids unnecessary component replacements.
