2016 Jeep Wrangler (3.6L) - Cylinder 6 Misfire P0306

J_Franzoni

New member
Hello,

I had my engine light come on and my scanner read "Cylinder 6 Misfire Detected P0306". I was tied up, so let my jeep sit for about a week and tried driving it around the block hoping it would go away, but now an additional code popped up "Random/Multiple Cylinder Misfire Detected P0300".

My jeep has 78,000 miles and although it has been serviced by the dealer and myself since I bought it new in 2016, I don't believe the spark plugs have ever been changed. Could this be the problem or does anyone have experience with this?

From my understanding, with the lovely design of this motor I have to remove the intake manifold just to get to the 2, 4, and 6 spark plugs and was hoping to not have to keep redoing this or spend a fortune on unnecessary parts to fix this.

Thank you,

Julian Franzoni
 

wayoflife

Administrator
Staff member
Me personally, I would have your dealership give it a look. It is entirely possible that you have a head issue. If so, this should be covered under warranty up to 100k if I remember correctly.
 

J_Franzoni

New member
Me personally, I would have your dealership give it a look. It is entirely possible that you have a head issue. If so, this should be covered under warranty up to 100k if I remember correctly.
Thank you, that was my first thought, but from what I see online the 2015 powertrain was up to 100K and of course the 2016 is 60K. I've been trying to work with a couple dealers in the area, but they are all short staffed and booked out 1-3 weeks.
 

krdadlamb

Caught the Bug
Thank you, that was my first thought, but from what I see online the 2015 powertrain was up to 100K and of course the 2016 is 60K. I've been trying to work with a couple dealers in the area, but they are all short staffed and booked out 1-3 weeks.
Our 2015 was the last year of the 100,000 mile warranty, and this issue was a head gasket, and covered under warranty. Hope things work out for you.
 

GP NOIR

Active Member
My 2012 with 132,000 miles on it recently had a #4 misfire code. The problem was caused by a bad ignition coil. I replaced all 6 coils and spark plugs and the engine runs like a dream.

Removing and reinstalling the intake turned out to be easy and straight forward. Spark plug holes are deep and a 19mm deep socket and a magnet were needed to get the plugs out.

Be very careful with the electrical connectors. They get brittle with heat and age and the locking tabs can be easily damaged. I had to secure a couple with a flat waxed string used for tying off wiring harnesses in aircraft to keep the connectors from coming loose.
 

J_Franzoni

New member
My 2012 with 132,000 miles on it recently had a #4 misfire code. The problem was caused by a bad ignition coil. I replaced all 6 coils and spark plugs and the engine runs like a dream.

Removing and reinstalling the intake turned out to be easy and straight forward. Spark plug holes are deep and a 19mm deep socket and a magnet were needed to get the plugs out.

Be very careful with the electrical connectors. They get brittle with heat and age and the locking tabs can be easily damaged. I had to secure a couple with a flat waxed string used for tying off wiring harnesses in aircraft to keep the connectors from coming loose.
On Saturday I decided to replace the spark plugs and the ignition coil for the 6th cylinder and so far so good. Those electrical connectors were a pain and a lot of the wire looms were crumbling and had to be replaced, so I'm sure I'll be using that stuff next. Thanks for the help.
 

J_Franzoni

New member
Our 2015 was the last year of the 100,000 mile warranty, and this issue was a head gasket, and covered under warranty. Hope things work out for you.
I was super bummed to find that out till I realized I was outside the timeframe anyways lol, but I swapped out the spark plugs and one of the ignition coils and so far so good. Thanks for the info.
 

GP NOIR

Active Member
Glad I was able to help.

On the left is the #4 ignition coil. On the right is an ignition coil from another cylinder for comparison

D8AAA105-90FE-4053-A269-9A96CBA7D575.jpeg
 

J_Franzoni

New member
Glad I was able to help.

On the left is the #4 ignition coil. On the right is an ignition coil from another cylinder for comparison

View attachment 376215
Damn! I thought stuff like that only happened to me lol. Was the rest of it easy to get out? I'm guessing I'll come across that sooner or later.

The new ignition coil I bought had a little bit of factory lubricant at the base that goes over the spark plug but since some of the ignition coils were hard to take out I added a little dielectric grease to each one.
 

GP NOIR

Active Member
Damn! I thought stuff like that only happened to me lol. Was the rest of it easy to get out? I'm guessing I'll come across that sooner or later.

I dug the rest out with a pair of needle nosed pliers. It was a minor annoyance. Had to blow all the crapola out with compressed air before removing the spark plug

The new ignition coil I bought had a little bit of factory lubricant at the base that goes over the spark plug but since some of the ignition coils were hard to take out I added a little dielectric grease to each one.

The coils I bought had no grease. So I used a bit of dielectric grease with each one.
 
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