When a burner clicks and never catches

Clicking is good news. It means the switch closed, the module fired, and there is a spark at an electrode somewhere. The fault is between that spark and the gas, and that is a short list.

Check the obvious first, in this order

Is the burner cap seated? A cap sitting even slightly proud of its seat, or rotated off its locating pin, puts the flame ports in the wrong place relative to the electrode. After a wash-up this is the most common cause of all, and it takes five seconds to rule out.

Is the cap dry? A cap or head washed and put back damp will spark enthusiastically and light nothing until it dries. If the burner started misbehaving the same evening the caps were cleaned, that is the answer.

Are the ports clear? Boil-over residue closes ports from the outside in. The port nearest the electrode is the one that matters — spark in one place and fuel in another lights nothing. A pin, gently, is the right tool; a drill bit is not.

Is the electrode clean and intact? Look at the ceramic. A crack in the insulator lets the spark track down to the nearest grounded metal instead of jumping the gap. You will still hear clicking. It just is not clicking anywhere useful.

Two things people assume and should not

The valve is almost never the problem. Valves are mechanical, they fail rarely, and they usually fail by being stiff rather than by not passing gas. If a technician’s first answer to a no-light is a valve, ask what test led there.

The spark module is also rarely the problem when the burner clicks, because a clicking burner proves the module works. The module becomes a suspect when burners spark continuously with every knob off, which is a stuck or wet switch loading the module, or when nothing sparks at all.

What the coast adds

Two things, both electrical rather than gaseous.

Salt film builds on the electrode and its insulator and survives an ordinary wipe. It does not stop the spark, but it gives the spark an easier path to ground than the one across the gap, which is functionally the same as a cracked insulator.

Humidity gets into the module housing and the harness terminals. Terminals tarnish, resistance climbs, and the spark energy at the electrode drops below what it needs to be. The classic presentation is a burner that lights fine in the afternoon and fights you first thing in the morning, when everything metal in the house is carrying dew.

Houses within sight of the dune line go through electrode assemblies faster than houses a few miles back. That is not a quality problem with the appliance.

Outdoors, add two more

On a built-in grill, an electrode bracket that has corroded has usually also moved, and a spark gap that is out by a millimetre or two will not light. And the crossover channel that carries flame from one burner to the next is exactly the kind of narrow passage that closes up outdoors — which is why an exposed grill often lights burner by burner but will not carry across.

When to stop and call

If the cap is seated and dry, the ports are clear, the ceramic is sound and it still will not light, the next steps involve gas pressure at the regulator and the flame-sense circuit. Those need a manometer and a meter, and they are not worth improvising around a live gas connection.

If you smell gas at any point, stop, shut the supply off, and do not use the appliance.