P0351 on Subaru: How to Diagnose & Fix
Ignition Coil A Primary/Secondary Circuit Malfunction
1 Subaru model · 1 documented issue · $60-$350 repair
P0351 on Subaru by model: symptoms, diagnosis and fix
Coil-on-plug ignition coils on the Forester are a common failure point. As the coil's internal epoxy/resin cracks with heat and age, the coil produces erratic or insufficient spark, causing single-cylinder misfires, rough idle, hesitation on acceleration, reduced fuel economy and a flashing/steady check-engine light. A frequently reported pattern is hard starting or stumbling when cold (below roughly 10°F) that improves once the engine warms. Note that a leaking spark plug tube seal (oil in the plug well) can prematurely kill a coil, so the two issues often appear together.
Common Symptoms
- Rough idle and vibration at idle
- Engine hesitation or stumble on acceleration
- Flashing or steady check engine light
- Hard starting or misfire when cold
- Reduced fuel economy
How to Fix
Pull codes — P0301-P0304 indicate the misfiring cylinder; P0351-P0354 indicate coil circuit faults. Confirm by swapping the suspect coil to an adjacent cylinder; if the misfire follows the coil, replace it (coils cannot be repaired). Inspect the plug well for oil and replace the spark plug tube seal if oil is present so the new coil isn't ruined. Replace the spark plugs at the same time. Forester ignition coil part numbers vary by year/engine (for example 22433AA691 on 2013-2018 2.5L and 22433AA590 on non-turbo 2009-2010); confirm the exact PN by VIN.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Subaru 22433AA590 Ignition Coil
single-cylinder replacement after the coil is proven failed Fitment/availability: 2009-2010 Forester 2.5L naturally aspirated X/X Limited/XS branch only; not XT, confirm VIN Fitment/availability: Add to Cart live when reviewed
- Genuine Subaru 22433AA630 Ignition Coil
single-cylinder replacement after the coil is proven failed Fitment/availability: 2011-2013 Forester 2.5L naturally aspirated X/X Limited/X Premium branch; not XT, confirm VIN Fitment/availability: ships in 1-2 business days with Add to …
- Genuine Subaru 22433AA682 Ignition Coil
single-cylinder replacement after the coil is proven failed Fitment/availability: 2014-2016 Forester 2.5i naturally aspirated branch; current replacement for 22433AA681/AA680, confirm VIN Fitment/availability: ships in 1-2 business days …
- Genuine Subaru 22433AA700 Ignition Coil
single-cylinder replacement after the coil is proven failed Fitment/availability: 2017-2018 Forester 2.5i naturally aspirated branch in this issue; retailer also catalogs XT, confirm VIN Fitment/availability: Add to Cart live when reviewed
- Genuine Subaru 22433AA770 Ignition Coil
single-cylinder replacement after the coil is proven failed Fitment/availability: 2019-2021 Forester Base/Premium/Sport/Limited/Touring branch; confirm VIN and production split Fitment/availability: ships in 1-3 business days with Add to…
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Sources for this issue (3)
P0351 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0351 mean on a Subaru?
P0351 stands for "Ignition Coil A Primary/Secondary Circuit Malfunction." P0351 indicates the engine computer found a fault in the primary or secondary circuit of ignition coil 'A' (typically the coil for cylinder 1 or the first coil in the firing system). The PCM monitors the coil's control circuit, and when the electrical feedback doesn't match what it expects during firing, it sets this code. Because the coil creates the high-voltage spark, this often causes a misfire, rough idle, hesitation, or loss of power. It is a circuit/component fault for one specific coil rather than a general engine problem. On Subaru it is documented across 1 model: Forester.
What are the most common causes of P0351?
The most common causes of P0351 are: Failed or weak ignition coil, Damaged or corroded coil connector or pigtail, Broken or shorted wiring in the coil control circuit, Loss of power feed or ground to the coil, Worn or fouled spark plug overloading the coil, Failed coil driver inside the PCM/ECM. The specific cause varies by vehicle.
How much does it cost to fix P0351 on a Subaru?
Published repair estimates on Subaru range from $60 to $350 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0351 on a different make?
View P0351 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.