2001 MDX Check Engine & VTM4 Lights On: P0305 and P1399 Codes Explained
My 2001 Mazda MX-5 (MDX) with 195,000 miles is running smoothly overall, but the Check Engine and VTM4 warning lights intermittently illuminate. The only diagnostic codes retrieved are P0305, which indicates a cylinder 5 misfire—possibly related to a faulty spark plug or coil pack—and P1399. I'm seeking clarification on what P13909 means in this context and how it should be addressed.
P1399 indicates a random misfire condition. Begin by inspecting the spark plugs and coil packs in cylinder 5. After replacing any worn components, clear the PCM memory and perform a road test to confirm whether the issue has been resolved.