High-Probability Causes:
* Ignition Coil(s): This is the most likely culprit. The ignition coil(s) provide the high voltage needed to ignite the spark plugs. A failing coil will produce weak or intermittent sparks, leading to misfires and ultimately burnt-out plugs. A failing coil can also cause rough idling. Inspect the coils visually for cracks or damage. A coil pack test is recommended.
* Worn-out or Cracked Distributor Cap and Rotor (if equipped): While less common on newer vehicles, some 2001 Caravans *might* still use a distributor. If so, a cracked or worn distributor cap and rotor can cause poor spark delivery and lead to similar symptoms. Replace both as a set if you find wear.
* Ignition Control Module (ICM): This is a less common failure point but can cause intermittent misfires and affect multiple cylinders, leading to burned-out plugs.
Medium-Probability Causes:
* Worn Spark Plug Wires: Cracked or damaged spark plug wires can leak voltage, leading to weak sparks and misfires. Visually inspect them for cracks, damage, or fraying.
* High Voltage Wiring Problems: This is a broad category. There might be some kind of short in the high-voltage wiring harness causing intermittent problems. This would require careful inspection by a mechanic.
Low-Probability Causes (but still possible):
* Fuel Issues: While less likely to directly cause spark plug failure, consistently poor fuel delivery (clogged fuel filter, weak fuel pump, etc.) can lead to lean conditions that can damage plugs over time. However, this would likely present other symptoms like hesitation or poor acceleration.
* Computer Issues (PCM): A faulty Powertrain Control Module (PCM) could be sending incorrect signals to the ignition system, but this is less likely than the other issues. This would usually require professional diagnosis.
* Crank Sensor/Cam Sensor: These sensors provide information about engine speed and position to the PCM. Faulty signals can lead to misfiring, but this again is less likely to directly cause repetitive spark plug failure alone.
Troubleshooting Steps:
1. Visual Inspection: Start by carefully inspecting the spark plug wires, ignition coils, distributor cap and rotor (if applicable). Look for any visible damage.
2. Spark Plug Wire Test (if applicable): Use an inline spark tester to check for consistent and strong sparks at each wire. A weak spark indicates a problem with the wire or coil.
3. Ignition Coil Test: Use a multimeter or a dedicated ignition coil tester to verify that each coil is working correctly.
4. Professional Diagnosis: If the above checks don't reveal a clear problem, it's time to seek professional help. A mechanic can perform a more thorough diagnostic test, including checking for codes stored in the PCM.
Important Note: Replacing spark plugs is usually a relatively straightforward repair. But the fact that they're burning out repeatedly indicates an underlying problem. Ignoring the root cause will continue to damage spark plugs and potentially lead to more significant engine damage.
