MoeB
09-04-2008, 05:57 PM
My CEL was randomly coming on for unknown reasons. For a while I suspected bad fuel because it would sometimes happen after filling up. Then I suspected tank contamination because it occasionally happened near empty. It did this over about a 20k mile span. Since it kept going off and the car otherwise ran fine, I would just ignore it.
This week I finally took it in for diagnostics and they found a catalytic converter sensor code indicating unburned fuel getting in the cat. They pulled the plug coils and found cracks in the plastic neck of all five coils. I'd done the 60k plugs myself and the coils looked OK then; however, I failed to pull down the rubber boot that covers the metal coil wire going to the plugs. The cracks looked pretty small to me, but apparently still big enough to leak current on one or more cylinders and allow unburned fuel out the exhaust. Tech said the cat would have eventually been toast if I hadn't caught it soon enough. He said he's even seen fuel from dead coils cause a valve to break off.
Anyway, I learned how to correctly inspect the coils for cracks by pulling off the rubber boot. I'll probably never use this info again, but thought I'd pass it on here.
This week I finally took it in for diagnostics and they found a catalytic converter sensor code indicating unburned fuel getting in the cat. They pulled the plug coils and found cracks in the plastic neck of all five coils. I'd done the 60k plugs myself and the coils looked OK then; however, I failed to pull down the rubber boot that covers the metal coil wire going to the plugs. The cracks looked pretty small to me, but apparently still big enough to leak current on one or more cylinders and allow unburned fuel out the exhaust. Tech said the cat would have eventually been toast if I hadn't caught it soon enough. He said he's even seen fuel from dead coils cause a valve to break off.
Anyway, I learned how to correctly inspect the coils for cracks by pulling off the rubber boot. I'll probably never use this info again, but thought I'd pass it on here.