Applicable Systems
OBD-II
Symptoms
Multiple cylinders misfiring; rough idle, power loss, possible catalytic converter damage; flashing CEL.
Possible Causes
- Multiple worn spark plugs
- Worn ignition coil(s)
- Lean mixture from vacuum leak
- Low compression in multiple cylinders
Troubleshooting Steps
- Step 1: Check spark plug condition and gap
Plugs in good condition, gap correct - Step 2: Inspect ignition coils for cracks/carbon tracking
Coils intact - Step 3: Check for vacuum leaks
No leaks found - Step 4: Perform compression test all cylinders
Compression within 10% across cylinders - Step 5: Replace faulty components
No misfire codes after repair
How to Reset
Clear with OBD-II scanner; clear fuel trims after repair. Flashing CEL = active misfire with cat damage risk.
Common Replacement Parts
- Spark Plugs (OEM spec)
- Ignition Coils
Frequently Asked Questions
- Q: What does flashing CEL mean?
Flashing CEL indicates active misfire severe enough to damage catalytic converter. Stop driving immediately and have vehicle towed for repair.
Comments (0)
Share your experience to help others facing the same problem.
Leave a Comment
Source: SAE J2012 standard DTC list + OBD-II portal
Category: OBD-II
Published: 2026-11-02
No comments yet. Be the first to share your experience!