On higher mileage vehicles, an engine misfire may develop and/or the Check Engine Light may illuminate due to a failed ignition coil. It is not uncommon to replace all the coils when the first one fails in order to prevent return trips to the repair shop.Google+
Car Problem Reports
Toyota Highlander Ignition Coil May Fail After 100,000 Miles
Toyota Highlander Problem
Average Mileage: 117,223 mi (80,000 mi - 204,000 mi)
Visitor, 2004 Toyota Highlander, 204,000 mi
check engine light on..4 different mechanics offered to install rebuilt engines...some with over 100000 miles for 4000-5000 bucks.one honest mechanic foreign auto worcester ma. james recognized the coil problem and painstakingly went thru entire engine and rep;aced all coils for alot cheaper than what everyone was saying.it took him over 20 hours to do the job....maybe thats why most mechanics take the easy way out
Visitor, 2002 Toyota Highlander, 85,000 mi
Engine running rough first mechanic replaced #1 coil and also ran an engine cleaner thru engine . Within week or two engine running rough again and second mechanic replaced same coil which went bad again
Visitor, 2003 Toyota Highlander, 85,000 mi
One coil went bad, at 84000 miles. My mechanic told me to replace all four, at same time. Replaced all four, then had 2 more replaced within a year that went bad. Now have another bad, which totals 7 that need replaced within a years time. If anyone would have any answers that would be great. I worked in a factory and understand that quality cannot be perfect all the time.
VSC light on and engine light flashing. Took to Toyota dealer to be fixed. Within 40 miles of having the new coils installed the VSC and engine light are both on. Took back to the dealer they reset codes, but think it may be the catalytic converter for a cost of $3200 (parts & labor)to replace. But after reading information on the website... I'm not sure if they checked the air filter hose connection so will check that first before replacing the catalytic converter.
Visitor, 2004 Toyota Highlander, 120,000 mi
Two ignition coils went out within a week.
Visitor, 2003 Toyota Highlander, 80,000 mi
Recurrent ignition coil problems about a year after they have been replaced.