CEL P0351 Ignition Coil "A" Primary Control Circuit/Open

[Icecreamtruk]

Originally Posted by strat61caster

That was last updated in March 2012, before the car even came out and has zero reference to new harness parts. It does involve testing the harness to ensure there are no faults in the wiring which is very useful information.

Aside from new part numbers for the coil packs to my knowledge there's nothing else the manufacturers have provided to reduce this happening. Maybe the updated parts are enough, maybe not. Fingers crossed from me and I look forward to hearing what you find out.

I do believe the '16 cars (and maybe '15's as well) changed connector types, but could be wrong. If that was a solution I would bet that there would be a TSB about upgrading the setup as it would be a real shit thing to do to not let techs/dealership/consumers know that this is a nearly 4-figure fix for the problem for a harness plus 4 coilpacks.

fwiw I changed all 4 spark plugs last week, you should be able to diagnose and swap without moving the engine I'd hope.

I will let you know if I find anything wrong with the harness, and/or if the coilpack for the 15-16 cars works on older models. Fingers crossed over here as well.

[solidONE]

Originally Posted by strat61caster

Yup, upon reviewing the pictures I've taken of the obd readings I've only roasted 1 & 2, I've gotten 4 codes two each of P0351 & P0352.

If you go back I mistakenly replaced #4 about two years ago, #1+2 got replaced last weekend so my #3 is OE after 4.5 years and 60k miles of abuse.

I guess it's actually a bit more random than just the right bank being too hot for the coils.

[strat61caster]

Originally Posted by solidONE

I guess it's actually a bit more random than just the right bank being too hot for the coils.

imo I think it has more to do with the qc or process involved in making the coil packs, some come out solid, some came out with latent weak points and the updated part numbers reflect a change to increase durability.

But we'll likely never know unless it becomes obvious that the new ones solve the issue.

[Ragin Gti]

Originally Posted by strat61caster

Which TSB? There was one that had nothing at all to do with the ignition coil issue and I just read the Toyota description of the issue from 2012 which just has the tech verify that the harness has no faults.



The latest coil pack part number for '13-'14 has the exact same connector as the original, I just installed two last week and all three part numbers in Subaru's system are listed as interchangeable.

Subaru TSB # 07-120-17. Dated 7/7/17. Coil part # 22433AA730. Harness # 24020AG080.


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[strat61caster]

Originally Posted by Ragin Gti

Subaru TSB # 07-120-17. Dated 7/7/17. Coil part # 22433AA730. Harness # 24020AG080.

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Looks promising, can't wait to read it. Now I don't feel bad for not knowing of it since it's less than a week old :P

From this website:
https://techinfo.subaru.com/search/listResults.html

Ignition Coils and Engine Harness- Design Changes to Address DTCs P0351, P0352, P0353 and / or P0354 This Service Information Bulletin announces design changes made to the ignition coil and engine wiring harness in response to a limited number of cases related to the ignition coil primary / secondary DTCs listed above. The changes involve a shape change to the harness connector on the coil and to the corresponding engine harness connector. A positive lock mechanism has also been added to the engine harness ignition coil connectors to reduce the chances of becoming disconnected and causing a driveability concern and / or DTC(s). Information contained in any technical document found on the STIS web site should only be used as reference material for highly trained automotive technicians. Only automotive technicians have the training and the special tools/equipment to repair Subaru vehicles. 07-120-17

[solidONE]

Originally Posted by Ragin Gti

Subaru TSB # 07-120-17. Dated 7/7/17. Coil part # 22433AA730. Harness # 24020AG080.


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That does not look like a cheap fix, or a quick one...

[Icecreamtruk]

Update: I changed the coilpack on cylinder 1 and performed vérifications for voltage and resistance on connectors (coilpack side for volt, from ECU to coilpack for resistance). All parameters are within spec. The connector doesnt seem loose, it actually has a clip mechanism and gigling it doesnt seem to trigger any missfires with the engine running. The coilpack we pulled out seems top shape, there are no sings of overheating, it even still had some grease on the pins.

I may start to think its the heat from inside the engine which is triggering this, rather than heat from the engine bay. In the time it sits between track sessions, it could be getting roasted from the inside.

I will report back when I get the 2016 coilpack and compare it to the 2013, to verify if it will fit or not.

[QTR FMS]

this might help instead of changing the whole harness and coils

Originally Posted by rocketbunny86

Mostly coil and spark plug at #3...if this doesn't solve your problem, check if you getting proper signal on th engine harness pin for coil plug #3.

I wasn't getting proper signal at my harness. So I tapped the wire coming from the ECU in the engine bay AC31 I think and connected it to coil #3 harness pin and problem solved.

Make sure the signal coming from the ECU is solid.

It's the heat soak in the engine bay and from the over pipe combined with real hot weather. Harness going haywire.

Hope this helps.

[Icecreamtruk]

In case anyone is still wondering. The 2015-2016 coilpacks do have infact a different conector type to the 2013-2014 ones. Im looking at both of them right now...

[Gords_zenith]

Hey guys. So ive been dealing with the P0351 DTC since the car was a year old, and have had the dealer swap the coils around numerous times. To the point that I changed the plugs and the issue went away, until now. So my question to you guys, I'm planning check the wire voltage and resistance of the harness in the future but reading the Manual that's posted above, they mention the coils overheating will also cause the DTC, so what temperature does this occur at? I'm at 100000 km now. And it's super annoying. I'm also looking into other parameters that could cause it. What should I log?

[Gords_zenith]

What does it mean when the check engine light comes and the traction light is flashing....or if the check engine is already on, what does it mean when the traction slip light flashes?

[strat61caster]

Originally Posted by Gords_zenith

What does it mean when the check engine light comes and the traction light is flashing....or if the check engine is already on, what does it mean when the traction slip light flashes?

I believe it means the car is slowing you down either via brakes on the wheels due to wheel slip or it's pulling throttle/timing out of the engine to protect it.

With regards to your earlier post, did you ever actually put new coil packs in or just swap them around?

Checking the harness is a good thing to do if new coil packs don't alleviate the problem, but once a coilpack is faulty it's faulty, it doesn't magically get better from what I can tell.

Put two new ones in a month ago and it feels like the car is much happier than before, could just be placebo but I'm optimistic that the latest part numbers exist to help prevent this from happening.

[df.dima]

I had the IC changed, a month in, so far so good. This is updated coil with part # I believe ending with 52 instead of 50 as the original part was.

[Gords_zenith]

Originally Posted by strat61caster

I believe it means the car is slowing you down either via brakes on the wheels due to wheel slip or it's pulling throttle/timing out of the engine to protect it.

With regards to your earlier post, did you ever actually put new coil packs in or just swap them around?

Checking the harness is a good thing to do if new coil packs don't alleviate the problem, but once a coilpack is faulty it's faulty, it doesn't magically get better from what I can tell.

Put two new ones in a month ago and it feels like the car is much happier than before, could just be placebo but I'm optimistic that the latest part numbers exist to help prevent this from happening.

Haven't put new coils in yet. But I think I understand the problem inducing criteria much better:
Problem (new readers) P0351 mil. car is stock (2013 early model VIn is 1800 problem started at 20K Km's, now at 101K) performed coil swapped 3 or so times, problem goes away for 15K-20k, new plugs at 96k.
1) Car needs to be warmed up (10-20 mins of driving) just cruising
2) ambient temps needs to be above 25C degrees
3) initially it started as problem when shifting at High RPMs and load 1-2 gear, now comes when downshifting to 3-4 gear and accelerating hard. Now comes in when shifting into 4th with full throttle

traction light flashes as mil is already on.....most likely pulling timing, my guess (doesn't abruptly slow down or feel like it stutters)

What I have done so far today trying to figure this out.
1) Pulled the coil, physically inspected it for the resin pulling up - looks ok, minor corrosion in the plug, seems unlikely
2) checked the connector for damage -ok
3) checked the wires for voltage and continuity as per the electrical service manual - seems ok

Likely cause in my opinion is heat induced resistance increase from the header below the cylinder or the cylinder head itself. The concensus on here is it's from the heat.....but nice to know they've updated the parts. Even if I can't get them warrantied I'm going to buy new ones anyways, but considering it doesn't change from cylinder to cylinder it's leading me to believe to be the plug ir harness even though the tests show it to be good.

Another thing is it could be an injector causing a lean condition under extended load......or a valve issue.....seems unlikely though.

I'm open to suggestions.........