2005 Chevy Equinox P0305 Fault Occurs Only When Raining
I experience a P0305 diagnostic trouble code exclusively when it rains. I have already replaced the spark plugs and ignition wires, but the issue persists. The problem appears to be weather-related, suggesting possible moisture-induced electrical faults in the ignition system.
Spray the #5 spark plug and ignition wire with a salt water solution to simulate wet conditions. Listen for a snapping sound indicating a secondary ignition wire short to ground. Check for visible sparking or arcing, especially in low light. Remove the #5 spark plug and inspect the insulator for cracks or carbon tracking—this was a common failure point. If no signs are found, swap the #5 spark plug with a known good plug from a non-misfiring cylinder. The fact that there's no misfire on the companion cylinder strongly suggests an ignition system issue, possibly due to moisture ingress.