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2018 A4 2.0T - Rough Idle, Misfires, and EPC Light On - P0301 Code

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Melissa G. · rep 0 · May 22, 4:21 AM · 1 replies · solved · Question

Hey everyone,

My 2018 Audi A4 2.0T Premium Plus has developed a really rough idle lately. It feels like it's shaking more than usual, especially when I'm stopped at a light. The EPC light came on a couple of days ago, and then the Check Engine Light (CEL) followed shortly after.

I hooked up my OBD-II scanner, and it's showing a P0301 code, indicating a misfire on cylinder 1. I've heard about carbon buildup issues on these engines, but I'm not sure if that's what I'm dealing with here. Could it be something simpler like a bad spark plug or ignition coil?

Any advice on where to start troubleshooting this? I'm hoping to avoid a costly trip to the dealership if it's something I can fix myself.

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 4:21 AM

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ClearTheCode guidance (Audi · Diagnostics & codes)

Summary: For 2018 A4 2.0T - Rough Idle, Misfires, and EPC Light On - P0301 Code, work through these steps on your 2016+ vehicle:

  1. Confirm the symptom — note when it happens (cold start, highway, after fuel fill, etc.).
  2. Scan codes — save all pending/stored DTCs; don't clear until you've recorded them.
  3. Check TSBs & recalls — look up your VIN for open campaigns and known fixes.
  4. Inspect the obvious — related fuses, connectors, fluid level, and recent repairs.
  5. Test the common fix — follow model-specific service procedures; one change at a time.
  6. Escalate if needed — burning smell, no brakes, overheating, or stalling in traffic → shop visit.

Owner reported: Hey everyone,

My 2018 Audi A4 2.0T Premium Plus has developed a really rough idle lately. It feels like it's shaking more than usual, especially when I'm stopped at a light. The EPC light came on a couple of days ago, and then the Check Engine Light (CEL) followed shortly after.

I hooked up my OBD-II scanner, and it's showing a P0301 code, indicating a misfire on cylinder 1. I've heard about car…

This is educational guidance, not a substitute for hands-on diagnosis.

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