Troubleshoot a portable indoor heater by identifying the nature of the problem, such as a piezo igniter that fails to spark or a burner that does not light. Then, go through a list of the possible causes of the issue, such as the list available on the Mr. Heater website.
If the piezo igniter on a portable heater does not spark, the issue may be that the spark electrode is in the wrong position. Resolving this issue involves either adjusting the spark gap or replacing the pilot assembly. Another potential source of the problem may be that the igniter cable is not attached to a spark electrode, in which case one should connect the cable to fix the heater. It is also possible that the spark electrode is broken or the piezo igniter is simply defective, in which case the proper protocol is to replace the pilot assembly or the control valve.
Another common issue with portable indoor heaters is that the burner fails to light after the pilot successfully lights. This may occur if there is a clog or blockage in the main burner orifice. Removing the clog with a cotton swab or cloth and alcohol is likely to restore the unit to working order. If there is not a clog or blockage, the problem may be that there is insufficient inlet gas pressure, requiring the gas cylinder be checked and potentially replaced.