P2308 on 2015-2016 Dodge Caravan: Ignition Coil 3 Circuit Causes and Fixes

What's Unique About the 2015-2016 Dodge CARAVAN

For the 3.6L Pentastar engine in the Dodge Caravan, this code points to a fault with cylinder #3. A critical point for this platform is that cylinder #3 is located on the rear bank (closer to the firewall), not the easily accessible front bank. This makes diagnosis and repair significantly more complex as it requires removing the upper intake manifold. Furthermore, a specific Technical Service Bulletin (TSB #18-069-16 Rev. A) for vehicles built between July 27, 2015, and September 11, 2015, notes that this code can be caused by a faulty PCM requiring complete replacement, not just a software update.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Check Engine Light is on or flashing
• Rough or shaking idle, engine vibrations are very noticeable
• Engine hesitates or stumbles during acceleration
• Noticeable loss of power
• Reduced fuel economy
• Engine may stall at idle

Most Likely Causes

1. Failed Ignition Coil #3 🔴 High Probability Ignition coils are wear items that fail from constant heat cycles in the engine bay. The rear bank where cylinder #3 is located can experience higher temperatures, potentially accelerating failure. Oil leaks from the valve cover gasket or spark plug tube seals, a known issue on the 3.6L Pentastar, can also saturate and destroy the coil boot.
   How to confirm: Because cylinder #3 is on the rear bank, a simple swap is labor-intensive. The proper method is to swap the coil from cylinder #3 with a coil from the front bank (e.g., cylinder #2). Clear the codes and run the engine. If the code changes to P2305 (Ignition Coil 2 Secondary Circuit), the coil is confirmed bad. This requires removing the intake manifold.
   Typical fix: Replace the faulty ignition coil. Given the labor required to access the rear bank, it is strongly recommended to replace all three rear ignition coils (#1, #3, #5) and all six spark plugs at the same time.
   Est. part cost: $25-$60 per coil
2. Worn or Fouled Spark Plug in Cylinder #3 🟡 Medium Probability Spark plugs have a 100,000-mile service life. A worn electrode, cracked porcelain, or fouling from oil or carbon can prevent a strong spark, causing the PCM to detect insufficient ionization.
   How to confirm: After accessing the rear bank and confirming the coil is good, remove the spark plug from cylinder #3. Inspect it for a worn-down electrode, cracks, or heavy oil/carbon deposits compared to a new plug.
   Typical fix: Replace the spark plug. It is best practice to replace all six spark plugs at the same time, especially since the intake manifold is already removed.
   Est. part cost: $8-$20 per plug
3. Damaged Wiring or Connector to Ignition Coil #3 ⚪ Low Probability The wiring harness runs behind the engine where it is exposed to high heat. The plastic connector can become brittle and break, and pins can corrode. In one documented case for a P2308 code, a user found a wet and corroded connector pin had rusted away, breaking the circuit.
   How to confirm: With the intake manifold removed, visually inspect the wiring harness and connector for cylinder #3. Look for broken locking tabs, corroded or recessed pins, and frayed or melted wires. A continuity test can be performed from the PCM connector to the coil connector if a visual inspection is inconclusive.
   Typical fix: Repair the damaged section of wire or replace the connector pigtail. This may involve soldering and heat-shrinking a new connector onto the harness.
   Est. part cost: $15-$40 for a pigtail connector

Rare But Worth Checking

• Faulty Powertrain Control Module (PCM): This is a rare but well-documented issue for this vehicle. TSB #18-069-16 Rev. A specifies that for vehicles built between July 27, 2015, and September 11, 2015, this code may be caused by a manufacturing defect in the PCM (improperly coated vent). The official fix is to replace the entire PCM module. Even on vehicles outside the TSB range, the coil driver circuit within the PCM can fail, which would also require PCM repair or replacement.
• Rocker Arm/Lifter Failure: A widespread issue on the 3.6L Pentastar is the failure of rocker arm bearings, leading to a 'ticking' noise and a loss of valve lift. While this typically sets a compression-related misfire code (like P0303), it's a critical pattern failure on this engine to be aware of during diagnosis if a new coil/plug doesn't resolve the misfire.

Diagnosis Steps

1. Confirm the presence of code P2308 (and likely P0303) with an OBD-II scanner.
2. Identify the cylinder layout. On the 2015-2016 Grand Caravan, the engine is mounted transversely. The bank closer to the radiator is the FRONT bank (cylinders 2, 4, 6, from passenger to driver side). The bank against the firewall is the REAR bank (cylinders 1, 3, 5, from passenger to driver side). Cylinder #3 is the middle cylinder on the difficult-to-access rear bank.
3. Check if your vehicle's VIN falls under TSB #18-069-16 Rev. A (build dates 07/27/2015 - 09/11/2015). If so, the likely cause is the PCM itself and dealer diagnosis is recommended.
4. If not covered by the TSB, proceed with physical diagnosis. This requires removing the upper intake manifold to gain access to the rear coils.
🎬 See how to properly remove the upper intake manifold.
5. Once accessed, swap the ignition coil from cylinder #3 with the coil from cylinder #2 (middle cylinder on the front bank).
6. Temporarily reinstall the intake manifold enough to safely run the engine. Clear the fault codes.
7. Start the engine and let it run until the check engine light returns. Re-scan for codes.
8. If the code has moved to P2305 (for cylinder #2), the ignition coil you moved is faulty. It is highly recommended to replace all three rear coils and all six spark plugs at this point.
9. If code P2308 returns, the problem is not the coil. Inspect the spark plug in cylinder #3 for wear or fouling. Also inspect the spark plug tube for any oil pooling, which indicates a leaking valve cover gasket.
10. If the plug is good, carefully inspect the wiring and connector for coil #3 for corrosion, damage, or loose pins. Also inspect the main engine harness connectors located under the air intake tube for corrosion or backed-out pins.
11. If all parts and wiring appear to be in good condition, the issue may be an internal failure of the PCM's coil driver circuit, which requires professional diagnosis and likely PCM replacement.

Parts You'll Likely Need

• Ignition Coil (OEM #05149168AI (supersedes 5149168AH, 5149168AJ)) — This is the most common failure point for a secondary ignition circuit fault. Due to the high labor cost to access the rear bank, it's wise to replace all three rear coils (1, 3, 5) at once.
  Trusted brands: Mopar, NGK, Denso, Delphi
  OEM price range: $45-$70
  Aftermarket price range: $25-$50
• Spark Plug (OEM #SP149125AE) — A worn or fouled spark plug is the second most likely cause. All six should be replaced during this job due to the 100k mile service interval and the labor involved.
  Trusted brands: NGK, Champion
  OEM price range: $15-$25
  Aftermarket price range: $8-$20
• Upper and Lower Intake Manifold Gaskets — These must be replaced anytime the intake manifold is removed to prevent vacuum leaks. They are not reusable.
  Trusted brands: Mopar, Fel-Pro, Mahle
  OEM price range: $30-$50 for a set
  Aftermarket price range: $15-$30 for a set

Related Codes That Often Appear With This One

• P0303 — P0303 means 'Cylinder 3 Misfire Detected.' Since P2308 indicates a lack of spark for cylinder 3, a misfire is the direct result and this code is almost always present as well.
• P0300 — This code for 'Random/Multiple Cylinder Misfire' can appear if the issue is intermittent or if the PCM fault described in TSB #18-069-16 is the root cause, as the bulletin lists P0300 as a primary symptom.

Technical Service Bulletins (TSBs) & Recalls

• 18-069-16 Rev. A: Supersedes the original TSB. Specifies PCM replacement for a narrow range of 2015-2016 vehicles (built 07/27/15-09/11/15) that set codes P2302, P2305, P2308, P2311, P2314, or P2317 due to a manufacturing defect.

Platform-Specific Known Issues

• TSB #18-069-16 Rev. A: This is a critical bulletin for vehicles built between July 27, 2015, and September 11, 2015. It states that codes like P2308 may be set due to a faulty PCM with an improperly coated atmospheric vent, leading to internal corrosion. The only fix is PCM replacement.

Mechanic-Grade Diagnostic Values

• Ignition Coil Primary Winding Resistance — expected: 0.6 to 0.9 Ohms at 77°F (25°C).. Failure: A reading significantly outside this range, or an open loop (OL) reading, indicates a faulty coil.
• Ignition Coil Secondary Winding Resistance — expected: 6,000 to 11,000 Ohms (6-11 kΩ).. Failure: A reading outside this range or an open loop (OL) reading indicates a faulty coil.
• Coil Control Circuit (K18) Test — expected: A test light connected to a 12V source should blink brightly while cranking the engine.. Failure: If the test light is ON constantly or OFF constantly, it indicates a fault in the PCM or the wiring between the PCM and the coil.
• ASD Relay Output Circuit (F342) Test — expected: A test light connected to ground should illuminate brightly when probed at the coil connector with the key on and the ASD relay actuated via a scan tool.. Failure: If the test light does not illuminate, there is an open or short to ground in the power supply circuit from the TIPM/fuse box.

Scan Tool Commands That Help

• wiTECH or equivalent professional scanner: ASD Relay Actuation — This command is used to manually turn on the Auto Shutdown (ASD) relay. It is essential for testing the integrity of the (F342) power supply circuit to the ignition coil without the engine running.
• wiTECH 2.0: Loss of Comm Test — For diagnosing intermittent electrical faults. This test repeatedly 'pings' all modules on the CAN bus. While performing a 'wiggle test' on the wiring harness, a technician can watch for the PCM or other modules to show 'no response', pinpointing the location of an intermittent open or short circuit.

Wiring & Ground Locations

• (K18) Coil Control 3 Circuit — The wire running from the PCM (C2 connector) to the #3 ignition coil connector.. This is the specific wire that carries the ground signal from the PCM to fire the coil. An open or short to ground on this wire will directly cause a P2308 code.
• (F342) ASD Output Circuit — The wire running from the TIPM (fuse/relay center) to the #3 ignition coil connector.. This wire supplies the 12V power to the ignition coil. A break in this wire will prevent the coil from charging, leading to a no-spark condition.
• Main Engine Harness Connectors — Two large, multi-pin connectors (often one black, one brown) located under the air intake tube, connecting the engine harness to the main body harness that goes to the PCM.. These connectors are a known weak point for water intrusion and corrosion. A single corroded or broken pin within these connectors that corresponds to the coil control or power circuit can cause an intermittent or persistent P2308, even if the coil and its pigtail are good.

Real Owner Repair Stories

• YouTube user PNWLevi (2008 Dodge Grand Caravan 3.8L (Note: different engine but same code and similar electrical failure mode)) — Engine running extremely rough, P2308 code for coil #3 failure.
  ❌ Tried (didn't work) Initial diagnosis pointed to the coil pack itself.
  ✅ What actually fixed it Found a wet and corroded main coil pack connector. The pin for the #3 coil control wire (blue with orange tracer) had completely rusted away and was missing. The fix was to cut the wire on both sides of the connector and run an external jumper wire to bypass the failed pin.
• YouTube user Timmy-G263 (2010 Dodge Caravan) — Code P2308, cylinder 3 misfire.
  ❌ Tried (didn't work) Began pulling apart the wiring harness looking for a short.
  ✅ What actually fixed it The problem was traced to the large harness connectors under the air breather tube. Corrosion was visible inside the connector, and the pin for the failing cylinder's coil circuit was broken off. The fix required repairing the pin/connector.

"I Checked Everything" — The Actual Cause

• In the context of this electrical code, the equivalent of a 'smoke test clean' scenario is when the coil, spark plug, and all external wiring test perfectly for continuity. In such cases, the root cause is almost certainly one of two things: 1) An intermittent connection that only fails under vibration or heat, often at a major harness connector. 2) An internal failure of the ignition coil driver transistor within the Powertrain Control Module (PCM), which requires PCM repair or replacement.

When the Usual Fixes Don't Work

• While a failed ignition coil is the most common cause, multiple documented cases show that after replacing the coil and spark plug, the P2308 code persisted. The ultimate fix was often found in the wiring harness, specifically at the large multi-pin connectors between the engine and the main vehicle body harness. Water intrusion leads to corrosion and broken pins, creating an open circuit that mimics a failed coil. Technicians and DIYers should thoroughly inspect these connectors before condemning the PCM if a new coil doesn't solve the issue.

OEM Part Supersession History

• 5149168AH → 05149168AI, 5149168AJ — Manufacturer updates to improve reliability, address failure patterns, or change suppliers. The core fit and function remain the same.
  Heads up: The listed part numbers (AH, AI, AJ) are generally interchangeable for the specified applications.

Model Year Variations Within This Range

• 2015 models built between 07/27/2015 and 09/11/2015: These vehicles are subject to Technical Service Bulletin #18-069-16. A P2308 code on these specific vehicles has a high probability of being caused by a defective Powertrain Control Module (PCM) due to an improperly coated vent, rather than a coil or wiring failure. The only prescribed fix is PCM replacement.