Car Won’t Start Or Runs Badly In Wet Weather
Starting problems or misfires in rain, fog or after washing usually mean moisture is reaching the ignition: cracked coils, worn plug leads, a damp distributor cap or water in connectors.
Normal risk
Have it checked soon. Moisture-related misfires can damage the catalytic converter.
Short answer · Why won't my car start when it is wet?
High voltage from the ignition coils finds the easiest path to ground. When coils or plug leads are cracked and damp, the spark leaks away instead of reaching the plug. Water in connectors or a blocked scuttle drain that floods the engine bay can also cause trouble. The problem often disappears once the engine dries.
Safe checks you can do
- Note the weather patternProblems only in damp conditions point to ignition leakage.
- Look at coils and leadsCracks or burn marks show where spark leaks.
- Check the scuttle drainLeaves can make water pour into the engine bay.
Questions that narrow it down
- Does it misfire in rain too?Ignition leakage is likely.
- Did it start after washing the engine?Water in connectors.
- Is the engine light flashing?Severe misfire; reduce load.
Possible causes
Listed without ranking. Use the questions above to see which ones fit your car.
- Cracked ignition coilSpark leaks to ground.
- Worn spark plug leadsOlder engines.
- Water in connectorsAfter washing or flooding.
- Blocked scuttle drainWater floods the engine bay.
Questions about Car Won’t Start Or Runs Badly In Wet Weather
Should I use moisture spray?
It can help temporarily, but cracked parts need replacing.
Can engine washing cause this?
Yes. Avoid pressure-washing electrical parts.