Rough idle and low RPM after engine warms up — ignition coil problem?

Home > Gari Forums > Haval Forums > Haval H6 Forums > Haval H6 Faulty Ignition Coil Forums

Rough idle and low RPM after engine warms up — ignition coil problem?

After driving for 10–15 minutes, my Haval H6 starts idling roughly and feels like it’s missing a beat. Spark plugs were replaced recently, but the issue remains. A friend told me that the ignition coils can get weak over time and cause this problem. How can I confirm if one coil is bad without replacing all of them?

Talha Kyanii asked on 25 Oct 2025 11:53:01 am

1 Answer

14 views |

Gari Master - on 25 Oct 2025 11:55:11 am

Yes, this could be an early sign of a weak ignition coil, especially if the issue happens after the engine heats up. Weak coils often work fine when cold but start failing as they expand with heat.

What to check:

Diagnostic scan: Use an OBD-II scanner to see if there’s a specific misfire code P0301–P0304.

Swap test: Mechanics often swap coils between cylinders — if the misfire moves to another cylinder, that coil is faulty.

Spark plugs: Even if they’re new, double-check the plug gaps and condition, since poor contact can make the coil misfire.

Recommendation:
Start with a diagnostic scan instead of replacing all coils. If one coil is confirmed weak, replace it with an original o r OEM-quality part. Also clean the throttle body and check for carbon buildup, which can worsen rough idling.