Hi. My Panasonic combination microwave oven recently started cutting out after 25-30 seconds, sometimes displaying the H98 error code. Purely by chance, I turned the oven through 180 degrees and discovered that the fan inlet grill at the rear was almost completely blocked-off by a sort of cobweb of greasy dust and fluff, which must have caused a significant reduction in cooling air over the magnetron, inverter and other electronic components. After a thorough clean with a dry brush, the oven was restored to normal. The air intake grill is out of sight, out of mind!
Sylvia Hodges, March 2017