Engine Misfire Due to Failed Spark Plug Wires on Subaru Forester

Problem Description and Possible Solution

Sometimes the Check Engine Light illuminates because the computer detects misfires. Subaru released an improved spark plug wire set to solve the problem. The ignition coil should also be inspected for carbon tracks or short circuits between the contacts

Problem Data
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Average mileage: 95,532 (40,869–205,183)
Engines affected: 2.5L 4 Cylinder, 2.5L 4 Cylinder Turbo
14 model years affected: 1998, 2000, 2001, 2002, more2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012, 2014
59 people reported this problem
Viewing 1 - 20 of 25 comments
Engine started to stutter at idle last night. After 5 min, it was fine and running perfectly. Next day, ran perfectly for 15 min, then started to stutter when idling. Check engine light and cruise control light are on now. Never had a problem with this car before.
No engine lights came on, but engine turned off at stop signs several times in the last week. The repair shop diagnosis is wires, oil change, spark plugs. It seems that if this is a common problem, it should be considered under the Lemon Law or covered under the warranty.
Drove home after a 100 mile trip around some twisty fun roads. Woke up the next day with the car throwing three codes. 02 sensor/Evap/Misfire cylinder 3. Just bought the car! What are the odds.
After starting he vehicle and going down the road {I have standard transmission} the car starts stalling and engine light starts blinking;
resolves itself after about 1/2 a mile; but only after a hard rain does this happen.
The check engine light came on and then the cruise control light. Next thing I know my Forrester is shaking left and right. The codes said missfire in cylinders 3 and 4, so I changed the spark plugs. The problem started back up 2 days later and I ended up have to replace the coil.
I installed a new set of Belden plug wires from NAPA. The issue came back. I completely removed the wires and the ignition pack to inspect it, reconnected everything, and the CEL went away. So all is well!
The check engine light illuminated and another dash light blinked continuously. I took it in to my mechanic, who said the wires and seals had to be replaced ($380). My friend had the same lights go off less than a week later and the Subaru dealer told her it was the catalytic converter.
Same as others stalled a few times, then ran fine. Today stalled repeatedly with check engine light on, cruise light flashing and slippery pavement light on. Diagnosed as cracked coil, fried spark plug wires and need to replace spark plugs.
Check engine light flashing, then going off. Eventually CEL stayed on. Diagnosed bad plug wires. They were just changed 1 year ago at 30,000 miles too. We'll see if thats the end of it.
8-9 hours into road trip check engine light came on. Dealership said to change spark plugs due to misfire. Did so. Next car trip same thing . About 3 weeks after plugs replaced. They mentioned ignition coil but tried to get check engine light to go off and couldn't . They Made a note in file. Told me when it goes off to not turn off car and drive straight to dealership ...but chances are they will be closed .
Consistent misfire on the cylinder 3. Replacing the coil helped for a while, then check engine light would go off, especially after wet weather. The last time the misfire was terrible, replacing wires and plugs helped. there was no need to replace the coil.
Misfire on Cylinder 2 & 4. Replace Spark plug wires but still misfire code. Replace engine coil and misfire code went away.
month ago, check engine and cruise lights on. subaru rec check gas cap. took it off and put back on. prob persisted.
3 days later, subaru svc could find no prob even tho the check eng came back as misfire. yesterday, car was dif to start and when put in gear, stalled. did not start after that. towed to subaru. result, ignition coil towers cracked and ignition wires burnt at coil. replaced. works fine.
Check engine light indicated misfire on #2 cylinder. Found spark plug wire was arching at/near coil. Replaced all plugs, wires and coil. Then same check engine light 2 months later indicating misfire on #2. This time found hole burnt through plug wire housing boot over actual spark plug which was arching onto manifold! Original problem occurred with original equipment wires and FR5AP-11 (NGK) spark plugs. Second incident happened after new coil, plugs and wires using OEM recommended NGK (55004) FX101 Spark Plug Wire Set and NGK (5464) IX Iridium Spark Plug
Was driving on the highway in fourth gear, rpm's were about 3 1/2 and before I shift to 5th my engine light comes on and flashes, I proceed to shift and the light stayed on but not flashing anymore. So I plugged my scanner into my car and it gave me a code that was related to cylinder 3 misfire ( I'm pretty sure it was 3 could be wrong) but it was a misfire code. I reset everything with the scanner and the light never came back on.
The car ran very rough, idled rough, and shuddered in waves especially at low speeds. The check engine light came on, sometimes solid, sometimes blinking, and with it the traction light and cruise control also malfunctioned. The dealer (mid city subaru in chicago) replaced wires and coil for $500. Another dealer (curry subaru in Mohegan Lake NY) did not detect any problem when the car was in for 60,000 mile service two months ago.