Challenger Coil Pack and Ignition Coil Replacement Guide
Failing ignition coils cause misfires and rough idle. Here's how to diagnose and replace them on the HEMI.
HEMI Ignition System Overview
The Gen III HEMI uses coil-on-plug (COP) ignition — one individual coil for each spark plug, mounted directly on the plug. The 5.7L (single plug per cylinder) has 8 coils; the dual-plug 5.7L and 6.4L have 16 coils; the Hellcat 6.2L uses 8 coils.
Symptoms of a Failing Coil
- P0300–P0308 misfire codes: A specific cylinder misfire code (P0301 = cylinder 1, etc.) usually points directly to the coil for that cylinder
- Rough idle or stumble
- Hesitation under acceleration
- Check engine light flashing (severe misfire can damage the catalytic converter)
Quick Diagnosis: The Swap Test
Before buying new coils, perform the swap test:
- Move the coil from the suspect cylinder to a known-good cylinder
- Clear the codes and drive
- If the misfire code moves to the new cylinder, the coil is bad
- If the code stays on the original cylinder, the problem is the plug, injector, or compression
Replacement Procedure
Tools: 8mm socket, ratchet, extension
- Remove the engine cover
- Disconnect the COP electrical connector (press tab, pull straight out)
- Remove the 8mm retaining bolt
- Pull the coil straight up and out
- Install new coil, reinstall bolt (snug — don't overtighten)
- Reconnect electrical connector until it clicks
Tip: Replace the spark plug at the same time — if the coil failed, the plug likely has extra wear.
OEM vs Aftermarket Coils
OEM Mopar coils are reliable and the safe choice: ~$30–40 each.
MSD Blaster coils are a popular performance upgrade — higher voltage output, especially beneficial on boosted engines where stock coils can struggle to fire through higher cylinder pressure.
Avoid: No-name coils from budget suppliers. Cheap coils often fail within 20,000–30,000 miles.
Replacing All 8 (or 16) at Once?
If one coil fails at 80,000+ miles, all coils have experienced similar wear. Replacing all of them at once saves labor on future individual replacements and eliminates subsequent misfires from other aging coils.
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