P0301 on 2011-2018 Volvo S60 2.5L T5: Cylinder 1 Misfire Causes and Fixes

What's Unique About the 2011-2018 Volvo S60

While ignition parts are a common cause of misfires on any car, some 2012-2016 Volvo 2.5L T5 engines (engine code B5254T12) are known for excessive oil consumption due to piston ring design. This issue can lead to spark plugs becoming fouled with oil and carbon, which is a frequent underlying cause of a P0301 misfire on this specific platform. Always inspect the spark plug from cylinder 1 for heavy, wet oil or black carbon deposits, as this may point to the deeper engine problem addressed by Volvo Technical Journal (TJ) 34588.

Symptoms You May Notice

• Rough or shaking idle.
• Hesitation or stumbling during acceleration.
• Flashing or solid Check Engine Light.
• Noticeable loss of engine power.
• Smell of unburnt fuel from the exhaust.
• Increased fuel consumption.
• Engine stuttering at high RPM (above 4,000-5,000 RPM) under load.

Most Likely Causes

1. Faulty Ignition Coil 🔴 High Probability → Shop Ignition Coil Coil-on-plug ignition systems have coils that operate under high heat and fail over time. It's a very common failure point for a single-cylinder misfire and a frequent topic in owner forums.
   How to confirm: Swap the ignition coil from cylinder 1 with the coil from another cylinder (e.g., cylinder 2). Clear the codes with a scanner and drive the car. If the code changes to P0302, the ignition coil is confirmed to be faulty. This is the standard first diagnostic step recommended by owners.
   Typical fix: Replace the failed ignition coil. It is often recommended by owners to replace all five coils at the same time, especially if they are original and the vehicle has high mileage, as others may fail soon.
   Est. part cost: $50-$90 per coil
2. Worn or Fouled Spark Plug 🔴 High Probability → Shop Spark Plug The B5254T12 2.5L T5 engine has a known oil consumption issue which can quickly foul spark plugs with carbon and oil, causing a misfire. Even without oil issues, standard wear requires replacement. A fouled plug is a very common cause of P0301 on this engine.
   How to confirm: Remove the spark plug from cylinder 1. Inspect it for a worn electrode, incorrect gap, cracks in the porcelain, or heavy, wet black/oily deposits. A heavily fouled plug is a strong indicator of the problem, and may point to the oil consumption TSB.
   Typical fix: Replace the spark plug. If the plug is heavily fouled with oil, it is crucial to investigate the root cause of oil consumption. It is best practice to replace all five spark plugs as a set with OEM-spec plugs (e.g., NGK or Bosch Iridium).
   Est. part cost: $10-$25 per plug
3. Clogged or Faulty Fuel Injector 🟡 Medium Probability → Shop Fuel Injector Fuel injectors can become clogged over time, leading to a lean misfire. While not specific to this platform, it's a common cause after ignition components are ruled out.
   How to confirm: After ruling out the spark plug and ignition coil, the fuel injector is the next likely cause. A professional can test the injector's flow rate. A more involved DIY test is to swap the cylinder 1 injector with another cylinder's injector to see if the misfire follows. One owner on Reddit with a P0301 and a related P0201 (Injector Circuit Malfunction) traced the issue to the injector.
   Typical fix: Replace the faulty fuel injector. It is often recommended to replace all five as a set to ensure balanced fuel delivery.
   Est. part cost: $50-$150 per injector
4. Carbon Buildup on Intake Valves ⚪ Low Probability As direct-injection engines, these T5s can be susceptible to carbon buildup on the back of the intake valves over time, which can disrupt airflow into the cylinder and cause a misfire, especially on cold starts. This is a known issue across many modern Volvo engines.
   How to confirm: This requires visual inspection, which involves removing the intake manifold to see the valve stems. A borescope can sometimes be used to inspect the valves with less disassembly.
   Typical fix: The intake valves need to be manually or media-blasted (walnut blasting) to remove the carbon deposits. This is a labor-intensive job often costing over $400 professionally.
   Est. part cost: $5-$20 for cleaning supplies, professional service is $400+

Rare But Worth Checking

• Low Engine Compression: This indicates a serious mechanical engine problem. A compression test is needed to confirm. On this engine, it could be related to the known oil consumption issue caused by faulty piston rings, which may require piston ring replacement as per Volvo TJ 34588.
• Vacuum Leak: A leak in a vacuum hose, intake manifold gasket, or a failing PCV system can lean out the air/fuel mixture and cause a misfire. A smoke test is the most effective way to find a leak. The PCV system diaphragm is a known failure point on P3 Volvos.
🎬 Watch: How to save money by replacing just the PCV diaphragm.

Diagnosis Steps

1. Read the freeze frame data with an OBD-II scanner to understand the engine conditions (RPM, load, temperature) when the code was set.
2. Visually inspect the wiring and connector for the cylinder 1 ignition coil and fuel injector for any obvious damage or looseness.
3. Swap the ignition coil from cylinder 1 to cylinder 2. Clear the codes, run the engine, and see if the code returns as P0302. If it does, the coil is bad. This is the most common and recommended first step.
4. If the misfire remains on cylinder 1, remove the spark plug. Inspect for wear, damage, or fouling. On this engine, look specifically for wet oil or heavy carbon deposits, which points towards the known oil consumption issue.
5. If the coil and plug are good, check the fuel injector. Use a 'noid light' to verify it's receiving a pulse from the ECM. Swapping the injector with another cylinder is the most definitive DIY test but is more involved.
6. Perform a compression test on all cylinders to check for mechanical engine issues. Low compression on cylinder 1 could confirm bad piston rings or a valve sealing issue.
7. Check for vacuum leaks using a smoke machine, paying close attention to the intake manifold gaskets and PCV system hoses. Perform a 'glove test' on the oil filler cap to check for excessive crankcase pressure, a sign of a clogged PCV system.

Parts You'll Likely Need

• Ignition Coil (OEM #30713417) — This is one of the most common failure items to cause a single-cylinder misfire. It's a relatively easy and quick part to replace during diagnosis. Note: Part number 31312514 is for later 4-cylinder engines and is not correct for this 5-cylinder.
  Trusted brands: Bosch, Denso, NGK, Volvo (OEM)
  OEM price range: $80-$120
  Aftermarket price range: $50-$90
• Spark Plug (OEM #30751806 (Volvo OEM)) — Spark plugs are a regular maintenance item and can become worn or fouled, especially on engines with known oil consumption issues. Using the correct OEM-spec plug is critical.
  Trusted brands: Volvo (OEM), NGK, Bosch
  OEM price range: $20-$30
  Aftermarket price range: $10-$20
• Fuel Injector (OEM #0280158096 (Bosch), 8653891 (Volvo)) — If the ignition system is healthy, a clogged or failed fuel injector is the next most likely component to cause a misfire in a single cylinder. This Bosch part number is widely cross-referenced for the 2.5L T5 engine.
  Trusted brands: Bosch
  OEM price range: $120-$200
  Aftermarket price range: $50-$150

Related Codes That Often Appear With This One

• P0300 — If the misfire is intermittent or begins to affect other cylinders, the generic 'Random/Multiple Cylinder Misfire' code P0300 may appear alongside P0301. This was seen in a detailed YouTube diagnosis where oil fouling was the root cause.
• P0302, P0303, P0304, P0305 — If there are underlying issues like poor fuel quality, a major vacuum leak, or systemic problems like severe carbon buildup, other cylinders may also log misfire codes.
• P0201 — This code for 'Injector Circuit/Open - Cylinder 1' points directly to an electrical fault or failure of the fuel injector in cylinder 1, making it a highly related code that pinpoints the cause of the P0301 misfire.

Technical Service Bulletins (TSBs) & Recalls

• TJ-34588: Addresses high oil consumption on 2013-2016 2.5L (B5254T12) engines, a potential root cause for fouled spark plugs. The service solution involves replacing the piston ring kit.

Platform-Specific Known Issues

• A Technical Service Bulletin (TSB TJ-34588) was issued for some 2013-2016 2.5L engines (B5254T12) for high oil consumption, which could require new piston rings. This can directly lead to P0301 by fouling the spark plug.

Mechanic-Grade Diagnostic Values

• Fuel Injector Resistance — expected: 12 - 16 Ohms. Failure: A reading outside this range indicates a faulty injector coil.
• Low-Side Fuel Pressure (at idle) — expected: ~300 kPa. Failure: Significantly lower pressure could indicate a weak fuel pump or clogged filter, though this would typically cause multiple misfires.
• Long-Term Fuel Trim (LTFT) — expected: Within +/- 10%. Failure: Values exceeding +/- 10% can indicate a fuel delivery imbalance, which could be caused by a faulty injector leading to a misfire.
• Spark Plug Gap — expected: 0.028 - 0.032 inches. Failure: An incorrect gap can cause weak spark and misfires, especially under load. Non-OEM plugs may come with an incorrect gap out of the box.

Scan Tool Commands That Help

• Volvo VIDA: Cylinder Compression Test — To perform a relative compression test without mechanical gauges. The software analyzes crankshaft speed variations during cranking to identify cylinders with low compression. This is useful for quickly checking mechanical engine health after ruling out spark and fuel.
• Volvo VIDA: Fuel Pressure Test — To read live data from the low-pressure fuel sensor. This allows a technician to monitor fuel pressure at idle and under load to diagnose fuel delivery issues without tapping into the fuel line.
• Volvo VIDA: Read Misfire Counters — To view the specific number of misfire events per cylinder. This is more granular than a simple P0301 code and can help determine the severity and frequency of the misfire, even if it's not bad enough to consistently keep the check engine light on.

Wiring & Ground Locations

• Engine Ground Strap — On earlier P2 platform Volvos, a key ground strap runs from the top of the engine near the timing belt cover to the chassis. While the P3 platform differs, ensuring the main engine-to-chassis ground is clean and tight is critical for stable ignition performance.. A corroded or loose engine ground can cause intermittent and hard-to-diagnose electrical issues, including weak spark leading to misfires. The ignition coils rely on a solid ground path to function correctly.
• Ground Point 31/4 — General designator for the main engine ground connection in Volvo wiring diagrams.. This is the primary ground return path for many engine components. Verifying its integrity is a key step in diagnosing any electrical fault, including an ignition system problem causing P0301.
• Ignition Coil Connector — Directly on top of each ignition coil, secured by a plastic tab.. The 4-pin connector provides power, ground, and a trigger signal from the ECM. The pins and wires at the connector can become brittle from heat cycles, leading to poor contact or breaks. Wiggling this connector while the engine is running can sometimes reveal a bad connection if the misfire changes.

Real Owner Repair Stories

• YouTube channel 'Not Enough Projects' (2012 Volvo S60 T5) — Stuttering under hard acceleration, flashing check engine light, hard cylinder 1 misfire (P0301), and eventually a P0300 (random misfire) as well.
  ❌ Tried (didn't work) Swapped cylinder 1 coil with a used junkyard coil, which did not fix the issue., Swapped spark plugs between cylinders; the P0301 code remained on cylinder 1, but a P0300 code was added, confusing the diagnosis.
  ✅ What actually fixed it Replacing all five spark plugs with new ones. The original plugs were heavily fouled from the engine's known oil consumption issue. The diagnostic confusion was caused by a faulty junkyard coil being used as a test part; the original coil was actually fine. The root cause was simply the oil-fouled spark plugs.

OEM Part Supersession History

• 8677837 → 30713417 — Standard part revision and update by Volvo.
  Heads up: The supersession is direct; the new part number replaces the old one for the same applications.

Diagnostic Flowchart

Other Known Issues on This Vehicle

Issues unrelated to this code that are worth knowing about as an owner of this generation:

• PCV System Failure 🔴 High — Common failure item, often cited to fail between 80k-100k miles. The diaphragm inside the oil filter housing tears, causing a loud whistle/squeal at idle, high crankcase vacuum, and potential oil leaks from blown seals.
• Aisin TF-80SC Automatic Transmission Valve Body Failure 🔴 High — Prevalent on earlier P3 models, but can still occur on 2011+ cars. Symptoms include harsh shifting, flares between gears, and a feeling of being 'bumped' from behind when stopping. Often caused by fluid breakdown and sticking solenoids in the valve body.
• Alternator Decoupler Pulley (ADP) Failure 🟠 Medium — The one-way clutch mechanism in the alternator pulley can seize or fail, typically after 80,000 miles. This causes a grinding or buzzing noise from the accessory belt area, especially after shutting the engine off from high RPM. Failure can strain the belt and tensioner.
• Excessive Oil Consumption (B5254T12 Engine) 🔴 High — Affects 2013-2016 models with the 2.5L T5 engine. Caused by faulty piston ring design, leading to oil burn-off, fouled spark plugs, and potential for low oil pressure warnings. (Ref: TJ-34588)
• Front Seat Belt Cable Fatigue 🔴 High — A recall was issued for a wide range of Volvo models, including the 2011-2018 S60. The steel cable connecting the seat belt to the front seat anchor can fatigue and break over time, compromising safety in a crash. (Ref: Recall R29970 / NHTSA 20V-144)

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: For this repair, using a used part is generally not recommended for the primary failure items. Ignition coils and spark plugs are wear items with a finite lifespan. A used coil from a junkyard could be near the end of its life or already faulty, complicating diagnosis as seen in a documented repair story. A used fuel injector is also a gamble due to the risk of internal clogging or wear.

Donor-vehicle mileage cap: roughly under 60000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• For an ignition coil, check for cracks in the plastic housing or melting near the boot.
• Ensure the electrical connector is not corroded or damaged.
• Ask for the donor vehicle's mileage; a low-mileage donor is always preferable.

OEM-only on this vehicle (don't cheap out):

• Spark Plugs: These engines can be very sensitive to the type of spark plug used. It is strongly recommended to use OEM Volvo plugs or the exact equivalent from NGK or Bosch to avoid introducing new misfire issues.

Aftermarket brands forum-validated for this vehicle:

• Ignition Coils: Bosch, Denso, NGK
• Fuel Injectors: Bosch (is the OEM supplier)
• Spark Plugs: NGK, Bosch (ensure it's the OEM-equivalent Iridium plug)

Brands owners have reported issues with on this vehicle:

• Unbranded, 'white-box' ignition coils and fuel injectors from online marketplaces. These often have high failure rates and can cause more problems than they solve.

Real Owner Stories

Aggregated from forums and TSBs cited above. Mileages and costs reflect what owners reported in those sources.

Related OBD-II Codes

• P0300 — Random or Multiple Cylinder Misfire Detected; often appears alongside P0301 when multiple coils are failing or oil consumption is fouling several plugs.
• P0302 — Cylinder 2 Misfire; this code will appear if you successfully swap a faulty cylinder 1 coil to cylinder 2 during the diagnostic process.
• P0201 — Injector Circuit Malfunction - Cylinder 1; specifically related to P0301 when the misfire is caused by a faulty fuel injector or its wiring.
• P0305 — Cylinder 5 Misfire; another single-cylinder misfire code common on this I5 engine when ignition coils or plugs reach the end of their service life.

Frequently Asked Questions