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2020 RAV4 XLE Rough Idle and Misfire Codes P0301, P0303

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Mike T. · rep 0 · May 22, 2:15 AM · 1 replies · solved · Question

Vehicle: 2020 Toyota RAV4 XLE

Hello everyone,

I'm having some trouble with my 2020 Toyota RAV4 XLE. Recently, it started running really rough, especially at idle, and the Check Engine Light came on. I pulled the codes and got P0301 (Cylinder 1 Misfire Detected) and P0303 (Cylinder 3 Misfire Detected).

The car feels sluggish, and there's a noticeable vibration when stopped. It's got about 60,000 miles on it. I haven't done the spark plugs yet, but I'm wondering if it could be something else like ignition coils or fuel injectors.

Any ideas on what I should check first? Is this a common issue for the 2020 RAV4? I'd like to try some basic troubleshooting before taking it to the dealership.

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 2:15 AM

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ClearTheCode admin answer:

The P0301 and P0303 codes on your 2020 Toyota RAV4 XLE indicate misfires in cylinders 1 and 3, respectively. Misfires can be caused by issues with the ignition system, fuel system, or engine mechanical components. Given your mileage, it's a good time to investigate.

Here's a systematic approach to diagnose the problem:

  1. Check Spark Plugs: Start by inspecting the spark plugs in cylinders 1 and 3. Look for signs of wear, fouling, or damage. If they haven't been replaced, this is a good starting point. You can also try swapping the spark plugs from a misfiring cylinder to a non-misfiring one to see if the code follows the plug.
  2. Inspect Ignition Coils: Each cylinder has its own ignition coil. A failing coil can prevent proper spark. Similar to spark plugs, you can swap the ignition coils from cylinders 1 and 3 with coils from known good cylinders (e.g., 2 or 4). If the misfire code then shifts to the new cylinder, you've identified a faulty coil.
  3. Fuel Injectors: Clogged or faulty fuel injectors can lead to a lack of fuel in a cylinder, causing a misfire. This is harder to diagnose without specialized tools, but you can sometimes listen for the clicking sound of injectors with a stethoscope or long screwdriver.
  4. Compression Test: If ignition and fuel delivery seem fine, a compression test can reveal mechanical issues like a worn piston ring, valve problem, or head gasket leak in the affected cylinders. Low compression in cylinders 1 and 3 would indicate a more serious internal engine problem.
  5. Vacuum Leaks: Less common for specific cylinder misfires, but a significant vacuum leak could affect overall engine performance and potentially contribute to misfires.

When to see a shop:

  • If swapping spark plugs and coils doesn't isolate the issue.
  • If you suspect fuel injector problems or require a compression test.
  • If the misfires are severe, causing the engine to shake violently, or if the Check Engine Light is flashing (indicating a severe misfire that could damage the catalytic converter).
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