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2020 Pacifica Misfire on Cylinder 3 - P0303 Code

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Rachel A. · rep 0 · May 22, 5:00 AM · 1 replies · solved · Question

Vehicle: 2020 Chrysler Pacifica Touring L

Hey everyone, I'm hoping someone can help me out. My 2020 Chrysler Pacifica Touring L started running really rough yesterday. The check engine light came on, and when I scanned it, I got a P0303 code, indicating a misfire on cylinder 3.

It's got about 75,000 miles on it. The idle is very shaky, and it feels like it's losing power, especially when accelerating. I haven't done any major maintenance on the spark plugs yet.

Any ideas on what I should check first? Is this a common issue with these vans?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 5:00 AM

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A P0303 code on your 2020 Chrysler Pacifica Touring L indicates that the engine's computer has detected a misfire in cylinder 3. This is a common diagnostic trouble code, and several issues can cause it. Addressing it promptly is important to prevent further damage, such as to the catalytic converter.

Here are the common causes and diagnostic steps:

  1. Faulty Spark Plug: This is often the most straightforward cause. Over time, spark plugs wear out, leading to inefficient combustion. A damaged or fouled spark plug in cylinder 3 could be the culprit.
  2. Defective Ignition Coil Pack: Each cylinder typically has its own ignition coil. If the coil for cylinder 3 is failing, it won't provide enough spark to ignite the fuel-air mixture.
  3. Clogged or Faulty Fuel Injector: An injector that isn't delivering the correct amount of fuel to cylinder 3 can cause a misfire. It might be clogged, stuck open, or not opening at all.
  4. Low Compression: Less common but more serious, low compression in cylinder 3 (due to worn piston rings, valve issues, or a blown head gasket) will prevent proper combustion.
  5. Vacuum Leak: A vacuum leak near cylinder 3 could lean out the fuel mixture, causing a misfire.

Diagnostic Steps You Can Take:

  1. Inspect and Replace Spark Plug: Start by removing the spark plug from cylinder 3. Look for signs of wear, oil fouling, or damage. If it looks worn, replace it. It's often a good idea to replace all spark plugs if they are due for maintenance.
  2. Swap Ignition Coil: To test the coil pack, swap the ignition coil from cylinder 3 with one from a different cylinder (e.g., cylinder 1). Clear the P0303 code. Drive the vehicle and re-scan. If the misfire code changes to P0301 (misfire on cylinder 1), then the coil pack you moved is faulty.
  3. Check Fuel Injector (Advanced): If the misfire doesn't move after swapping the coil, the issue might be the fuel injector. This often requires specialized tools to test its resistance or pulse, or a mechanic can perform a 'noid light' test.

When to See a Shop:

If you've replaced the spark plug and swapped the ignition coil without resolving the P0303 code, or if you're uncomfortable performing these diagnostic steps, it's highly recommended to take your Pacifica to a qualified mechanic. They have advanced diagnostic equipment to accurately test fuel injectors, perform compression tests, and check for vacuum leaks or wiring issues that might be causing the misfire. Ignoring a persistent misfire can lead to more expensive repairs down the line, especially involving the catalytic converter.

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