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Rough Idle and Misfire on 2020 CT5 2.0T - P030X codes?

0

Dan C. · rep 0 · May 24, 1:41 PM · 1 replies · solved · Question

Hey everyone,

I've been experiencing a really rough idle in my 2020 Cadillac CT5 Luxury with the 2.0T engine. It feels like the car is shaking a bit, especially when I'm stopped at a light. The check engine light came on a couple of days ago, and I pulled some codes with my OBD-II scanner.

I'm getting a P0300 (random/multiple cylinder misfire detected) and a P0302 (cylinder 2 misfire detected). The car has about 45,000 miles on it. I'm wondering if this is a common issue for the 2.0T in these CT5s and what some of the usual culprits might be.

Has anyone else dealt with this? Any advice on where to start troubleshooting before I take it to the dealership? Thanks in advance!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 24, 1:41 PM

0

ClearTheCode guidance (Cadillac · Engine & drivetrain)

Summary: For Rough Idle and Misfire on 2020 CT5 2.0T - P030X codes?, 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,

I've been experiencing a really rough idle in my 2020 Cadillac CT5 Luxury with the 2.0T engine. It feels like the car is shaking a bit, especially when I'm stopped at a light. The check engine light came on a couple of days ago, and I pulled some codes with my OBD-II scanner.

I'm getting a P0300 (random/multiple cylinder misfire detected) and a P0302 (cylinder 2 misfire detected). …

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

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