Repair Safety Notice:
This information is for general instructional purposes only. Vehicle repair can be dangerous.
Verify all information, follow manufacturer service procedures, use proper tools and safety equipment,
and consult a qualified repair shop when needed.
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MHPAUTOS
CAR REPAIR CONTRIBUTOR
31,937 POSTS
Hi there,
If one plug was dead, you would get a higher HC reading in the exhaust, but foe an over all over rich mixture i would be looking foe a faulty O2 sensor.