P0302 on 2001-2009 Volvo S60 2.5T: Cylinder 2 Misfire Causes and Fixes

What's Unique About the 2001-2009 Volvo S60

The 2001-2009 Volvo S60 belongs to the 'P2' platform, and its 2.5T 5-cylinder engine uses a coil-on-plug ignition system. These individual ignition coils are a very common failure point and the most frequent cause of single-cylinder misfires like P0302. While other issues can cause a misfire, owner experiences overwhelmingly point to starting with the ignition coil as the most probable culprit before spending time or money on more complex diagnostics. The plastic connectors for the coils are also known to become brittle and break, causing a loose connection.

Symptoms You May Notice

• Rough or vibrating idle
• Hesitation or stumbling during acceleration
• Noticeable loss of engine power
• Flashing Check Engine Light (especially under load)
• Reduced fuel economy
• Difficulty starting the engine
• Engine sounds different or has a changed rhythm

Most Likely Causes

1. Faulty Ignition Coil 🔴 High Probability → Shop Ignition Coil The coil-on-plug units used on this engine are a known high-failure item due to age and repeated heat cycles in the engine bay. They are the most common cause of a single-cylinder misfire.
   How to confirm: Swap the ignition coil from cylinder 2 with the coil from an adjacent cylinder (e.g., cylinder 3). Clear the codes and drive the vehicle. If the code changes to P0303, the coil is confirmed bad. This is the universally accepted first diagnostic step in owner forums.
   Typical fix: Replace the faulty ignition coil. It is held in by a single 8mm or 10mm bolt 🎬 Watch: Step-by-step guide to replacing your ignition coils. and is easily accessible after removing the plastic engine cover. Many owners recommend replacing all five coils if they are original, as the others are likely to fail soon.
   Est. part cost: $50-$90
2. Worn or Fouled Spark Plug 🟡 Medium Probability → Shop Spark Plug Spark plugs are a regular maintenance item with a replacement interval of around 30,000 to 60,000 miles for this vehicle. If they are old, have an incorrect gap, or are fouled by oil or carbon, they can cause misfires.
   How to confirm: After ruling out the coil, remove the spark plug from cylinder 2. Inspect it for wear (rounded electrode), heavy carbon buildup, or oil fouling. Compare it to a plug from a healthy cylinder. A plug in bad condition is a clear indicator.
   Typical fix: Replace the spark plug. It is highly recommended to replace all five spark plugs at the same time for consistent performance and to prevent future misfires. Use plugs from an OEM supplier like Bosch or NGK, or genuine Volvo plugs, gapped correctly.
   Est. part cost: $40-$80 for a set of 5
3. Clogged or Faulty Fuel Injector ⚪ Low Probability → Shop Fuel Injector
   How to confirm: If the misfire remains on cylinder 2 after swapping the coil and plug, the injector is the next suspect. An advanced DIYer can swap the injector with another cylinder to see if the misfire follows. A professional can perform a flow test. Sometimes a user on a forum will find the injector is visibly clogged upon removal.
   Typical fix: Replace the faulty fuel injector. Sometimes, running a high-quality fuel system cleaner can resolve minor clogging issues, but replacement is often necessary for a failed injector.
   Est. part cost: $70-$150

Rare But Worth Checking

• Vacuum Leak: A leak in a vacuum hose or intake manifold gasket near the cylinder 2 runner can cause a lean misfire. This would likely be accompanied by other codes (like lean codes) or a rough idle that improves with RPM.
• Low Cylinder Compression: This is a serious mechanical issue, such as a burnt valve or worn piston rings. A compression test is needed to diagnose this. A forum user reported a P0302 on a V70R, and after swapping the coil and plug with no change, a compression test revealed 0 PSI in cylinder 2, indicating a burnt valve. This serves as a good example of the full diagnostic tree.
• Damaged Coil Connector/Wiring: The plastic connectors and wiring for the ignition coils can become brittle and crack over time due to engine heat, leading to a poor connection and an intermittent misfire. A user on Reddit reported all 5 connector latches were broken on their 2001 S60, causing a coil to wiggle loose and trigger a misfire. Repair kits with new connectors and wire pigtails are available.

Diagnosis Steps

1. Read the code with an OBD-II scanner to confirm P0302.
2. Remove the plastic engine cover (typically held by Torx bolts) to access the ignition coils.
3. Cylinder 2 is the second cylinder from the timing belt side (which is the passenger side in US models).
4. Swap the ignition coil from cylinder 2 with the coil from cylinder 3.
5. Clear the diagnostic trouble codes using the scanner.
6. Drive the vehicle until the Check Engine Light returns.
7. Scan for codes again. If the code is now P0303, the ignition coil is faulty and needs replacement.
8. If the code remains P0302, the coil is likely good. Return it to its original position.
9. Repeat the swap process with the spark plugs between cylinders 2 and 3. Clear codes and re-scan after driving.
10. If the code is now P0303, the spark plug is faulty. Replace all five plugs.
11. If the code remains P0302, inspect the ignition coil connector for cracks or damage. Wiggle the connector with the engine running to see if it induces a misfire.
12. If the issue persists, the problem is likely a fuel injector, wiring, or a mechanical problem requiring further diagnosis like a fuel pressure test or a cylinder compression test.

Parts You'll Likely Need

• Ignition Coil (OEM #30713416) — This is the most common failure part for a single-cylinder misfire on the Volvo 2.5T engine.
  Trusted brands: Bosch (OEM), Denso, Genuine Volvo
  OEM price range: $80-$100
  Aftermarket price range: $50-$75
• Spark Plug (OEM #8692071) — A worn spark plug is the second most likely cause. They are a standard maintenance item and should be replaced if their age is unknown.
  Trusted brands: Bosch (OEM), NGK, Genuine Volvo
  OEM price range: $12-$18 per plug
  Aftermarket price range: $8-$15 per plug
• Ignition Coil Connector Pigtail (OEM #KIT-528493 (Genuine Volvo Repair Kit)) — Needed if the original plastic connector has broken, which is a common issue. These kits allow you to splice in a new connector.
  Trusted brands: Genuine Volvo, Aftermarket kits
  OEM price range: $25-$40 per connector
  Aftermarket price range: $10-$20 per connector

Related Codes That Often Appear With This One

• P0300 — If the misfire becomes more frequent or other cylinders begin to misfire, a P0300 (Random/Multiple Misfire Detected) code may appear alongside P0302.
• P0301, P0303, P0304, P0305 — If other single-cylinder misfire codes are present, it may point to a more systemic issue like a vacuum leak, fuel pressure problem, or a failing component that affects multiple cylinders.

Platform-Specific Known Issues

• The plastic clips on the ignition coil connectors become extremely brittle with age and heat, often breaking when you attempt to disconnect them. This can lead to a poor connection that mimics a failing coil. Zip ties are a common temporary fix, but replacing the connector is the correct repair.
🎬 Watch: How to fix a broken ignition coil connector.

Mechanic-Grade Diagnostic Values

• Ignition Coil Connector Power Supply Voltage — expected: Approximately 11-12V (Battery Voltage). Failure: Significantly lower or no voltage indicates a power supply issue to the coil.
• Fuel Injector Resistance — expected: 12.2 - 12.5 Ohms. Failure: A reading significantly outside this range suggests a faulty injector coil.
• Fuel Injector Pulse Width (Advanced) — expected: Consistent response down to 0.7 - 1.5 ms. Failure: Inconsistent or no pulse signal on an oscilloscope points to a wiring or PCM driver issue.

Hidden / Shadow Codes Worth Checking

• Mode 6, MID: $A2, TID: $0C: Misfire counts for the current or last driving cycle. This allows viewing of misfire events that have not yet reached the threshold to trigger a P0302 code and Check Engine Light. (see via An advanced OBD-II scanner that supports Mode 6 diagnostics. The data shows raw misfire counts per cylinder, helping to confirm which cylinder is the problem, even with intermittent issues.)

Scan Tool Commands That Help

• Volvo VIDA: Live Data Monitoring — While a generic scanner shows basic data, Volvo's own diagnostic software (VIDA) provides more detailed, real-time parameter lists for the engine management system. It can be used to monitor misfire counters and related sensor data with higher fidelity to pinpoint intermittent or unusual causes that don't set a hard fault.

Wiring & Ground Locations

• Ignition Coil Connector (Cylinder 2) — On top of the engine, second coil from the passenger side (timing belt side).. The Green/White wire is the 12V power feed. The other wire (color may vary, e.g., Yellow) is the trigger signal from the PCM. Checking for voltage at the Green/White wire is a key step in diagnosing a 'no spark' condition.
• G2 (or similar) — A common engine compartment ground point is located on the left (driver's side in US) inner fender, near the strut tower.. A poor engine ground can cause a weak spark and lead to intermittent misfires across multiple cylinders, though it can sometimes manifest as a single cylinder misfire initially.
• 31/44 — A ground connection located on the left-hand side member in the lower engine compartment.. This is another critical ground point for engine electronics. Corrosion or a loose connection here can cause a variety of difficult-to-diagnose electrical issues, including misfires.

Real Owner Repair Stories

• Reddit user in r/MechanicAdvice (2005 Volvo S60 2.5T) — Misfire on cylinder 4 (P0304), rough running, flashing check engine light, loss of power.
  ❌ Tried (didn't work) Installing a new Duralast ignition coil from AutoZone., Installing a new OEM Bosch ignition coil from FCP Euro as-is.
  ✅ What actually fixed it The new aftermarket and OEM coils had rubber boots that were about 1/4 inch too long, preventing them from seating correctly on the spark plug. The final fix was to take the shorter rubber boot from the original failed coil and install it on the new Bosch coil, which then fit perfectly and resolved the misfire.
• Volvo Forums user (2005 S60) — Misfire on cylinder 2.
  ❌ Tried (didn't work) Initially replacing parts without confirming the fault.
  ✅ What actually fixed it The owner swapped the ignition coil from cylinder 2 to cylinder 3. The code reader then showed a P0303 misfire, confirming the ignition coil was the faulty component. Replacing the single bad coil fixed the issue.

OEM Part Supersession History

• 30713416 → 30713416 (current) — This part number appears stable for the specified vehicle range.
  Heads up: While the part number is stable, a real-world incompatibility was reported where the rubber boot on new OEM Bosch coils (P/N 0-221-604-008, which corresponds to Volvo 30713416) was too long for a 2005 model, requiring the boot from the old coil to be swapped over for a proper fit.

Model Year Variations Within This Range

• 2001, 2005, 2006: According to one automotive complaint aggregation site, these specific model years are listed as 'years to avoid' for the S60, citing a higher-than-average number of complaints, including engine and transmission troubles. This may suggest a higher propensity for component failures leading to codes like P0302, but does not point to a different root cause.

Diagnostic Flowchart

Other Known Issues on This Vehicle

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

• Clogged PCV/Breather System 🔴 High — Common on vehicles over 80,000-100,000 miles, especially with infrequent oil changes. A 'glove test' (placing a rubber glove over the oil filler neck) that inflates indicates a clogged system.
• Electronic Throttle Module (ETM) Failure 🔴 High — Very common on 1999-2002 models, leading to a warranty extension. Can cause erratic idle, stalling, and 'limp mode'. Less common on later years but still a known failure point. (Ref: Volvo extended the warranty to 10 years/200,000 miles in the US for this part on early models.)
• Driver Information Module (DIM) Failure 🟠 Medium — Common on 2002-2006 models, causing intermittent or total loss of the instrument cluster, flickering lights, and erratic gauges. Often requires sending the unit for professional repair.
• AWD Angle Gear Collar Sleeve Failure 🟠 Medium — A common failure point on AWD models, where the splines on the sleeve connecting the transmission to the angle gear strip out, resulting in loss of AWD. An improved part was used from 2006 onwards, but earlier models are prone to this 'silent failure'.
• Automatic Transmission Valve Body/Solenoid Failure 🔴 High — Frequent in higher mileage vehicles (80,000-120,000+ miles), causing harsh shifting, delayed engagement, and slipping. Often related to the Aisin-Warner AW55-50/51 transmission.

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: For this specific repair, buying used parts is generally not recommended. While a user reported temporary success with a junkyard coil, the high failure rate of ignition components and the relatively low cost of new parts make new the smarter choice. Structural components like an intake manifold or engine covers are suitable used parts, but not the electronic components that cause this code.

Donor-vehicle mileage cap: roughly under 100000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• For ignition coils, there are no reliable visual cues. For connectors, check for intact locking tabs and non-brittle plastic.
• If sourcing a used engine component, look for a donor vehicle with a documented history of regular maintenance and no signs of overheating.

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

• Ignition Coils
• Spark Plugs

Aftermarket brands forum-validated for this vehicle:

• Bosch (This is the Original Equipment Manufacturer for the ignition coils and plugs)
• Delphi (Mentioned by a forum user as a viable aftermarket coil option)

Brands owners have reported issues with on this vehicle:

• Unbranded or generic 'value' brand coil sets from online marketplaces. Forum users express skepticism about their longevity and fitment, and real-world stories show fitment can be an issue even with reputable brands.

Real Owner Stories

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

Related OBD-II Codes

• P0303 — This code indicates a misfire on cylinder 3; it is used during the diagnostic process to confirm a faulty coil or plug by swapping components from cylinder 2 to cylinder 3.
• P0300 — A random/multiple cylinder misfire code that may appear if multiple ignition coils or spark plugs are failing simultaneously due to age.
• P0301 — Cylinder 1 misfire; shares the same root causes as P0302, such as failing coil-on-plug units or worn spark plugs.
• P0304 — Cylinder 4 misfire; another companion code common on the I5 engine when ignition components reach the end of their service life.
• P0305 — Cylinder 5 misfire; frequently associated with broken plastic clips on the ignition coil connectors in high-mileage S60 models.

Frequently Asked Questions