P0306 on 2016-2017 Ford Edge: Cylinder 6 Misfire Causes and Fixes

What's Unique About the 2016-2017 Ford EDGE

For the 2016-2017 Ford Edge, P0306 on V6 models is more than just a standard misfire code. On the 2.7L EcoBoost engine, particularly those built between April 1, 2016, and January 1, 2017, Ford has issued Technical Service Bulletins (TSBs) linking this code to excessive oil consumption caused by faulty valve guides, which may require cylinder head replacement. On the 3.5L V6, a failing ignition coil can short internally and send a voltage spike that damages the engine computer's (PCM) driver circuit, turning a simple fix into a costly repair. This makes proper diagnosis more critical than on many other vehicles.

Diagnostic Flowchart

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

Symptoms You May Notice

• Rough or shaky engine idle
• Hesitation or stumbling during acceleration
• Noticeable loss of engine power
• Check Engine Light is on and solid
• Check Engine Light is flashing (indicates a severe misfire)
• Strong smell of raw fuel from the exhaust
• White or blue smoke from the exhaust, especially after a hot restart (specific to 2.7L TSB issue)
• Oil on spark plug boots or in spark plug wells (can indicate a leaking valve cover gasket)

Most Likely Causes

1. Faulty Ignition Coil 🔴 High Probability → Shop Ignition Coil Coil-on-plug systems are common failure points due to constant heat exposure. On the 3.5L V6 engine, a failing coil can short out and send a voltage spike back to the PCM, damaging the driver for that cylinder. This makes it a critical component.
   How to confirm: Swap the ignition coil from cylinder 6 with another cylinder (e.g., cylinder 5). Clear the codes and drive. If the code changes to P0305, the coil is bad.
   Typical fix: Replace the faulty ignition coil. It is highly recommended to replace the corresponding spark plug at the same time.
   Est. part cost: $40-$80
2. Worn or Fouled Spark Plug 🔴 High Probability → Shop Spark Plug Spark plugs are a regular maintenance item with a finite lifespan. On V6 models, worn plugs can strain the ignition coils, leading to their premature failure and potential PCM damage. EcoBoost engines are particularly sensitive to correct spark plug heat range and gap.
   How to confirm: After confirming the coil is good, remove the spark plug from cylinder 6. Inspect it for wear (worn electrode), carbon or oil fouling, or cracks in the porcelain insulator. Replace if it is worn or past its service life.
   Typical fix: Replace the spark plug in cylinder 6. It is best practice to replace all six spark plugs at once for even performance and to avoid repeated labor, especially for the hard-to-access rear bank.
   Est. part cost: $10-$25 per plug
3. Internal Engine Failure (2.7L EcoBoost) ⚪ Low Probability TSBs 19-2243 and 19-2384 specifically identify 2016-2017 models with the 2.7L EcoBoost engine built between April 1, 2016, and January 1, 2017 as being prone to excessive oil consumption due to faulty valve guides. This allows oil to enter the cylinder, fouling the spark plug and causing misfires.
   How to confirm: Monitor for excessive oil consumption (1 quart in less than 3,000 miles), rough idle, and white/blue exhaust smoke. A professional should perform an engine compression test and cylinder leak-down test to confirm internal failure. This is not a simple DIY diagnosis. 🎬 See how a mechanic diagnoses 2.7L EcoBoost misfire issues.
   Typical fix: Replacement of both left and right cylinder heads, as per Ford's TSBs. This is a major and expensive repair covered under warranty if the vehicle qualifies.
   Est. part cost: $1500-$3000+
4. Clogged or Faulty Fuel Injector 🟡 Medium Probability → Shop Fuel Injector
   How to confirm: If the spark and ignition systems are confirmed good, the fuel injector is a likely cause. A mechanic can perform a fuel injector balance test. Sometimes, a P0206 code (Injector Circuit/Open Cylinder 6) will accompany the P0306, pointing directly to the injector or its wiring.
   Typical fix: Replace the fuel injector for cylinder 6. Some owners on forums have noted that an injector can stick when hot, causing an intermittent misfire.
   Est. part cost: $70-$150

Rare But Worth Checking

• Damaged Powertrain Control Module (PCM): → Shop Engine Control Module (ECM) On the 3.5L V6, a failed ignition coil can short out and damage the PCM's driver circuit. If a P0356 code is present or if a P0306 code immediately returns after replacing the coil and plug, the PCM is the likely root cause and must be replaced or repaired.
• Vacuum Leak: A leak in the intake manifold gasket near cylinder 6 could lean out the air/fuel mixture and cause a misfire. This would typically be accompanied by a hissing sound from the engine bay and possibly lean codes (P0171/P0174).

Diagnosis Steps

1. Read the codes with an OBD-II scanner to confirm P0306 and check for any other related codes (e.g., P0356, P0206, P0300).
🎬 Watch: Helpful walkthrough for troubleshooting the P0306 engine code.
2. Identify cylinder 6. On the transverse V6 engines in the Edge, the cylinders are numbered 1-2-3 on the rear bank (against the firewall) and 4-5-6 on the front bank (near the radiator), arranged from passenger side to driver side. Cylinder 6 is the front-most cylinder on the driver's side.
3. Swap the ignition coil from cylinder 6 with the coil from cylinder 5 (the middle cylinder on the front bank).
4. Clear the codes and drive the vehicle until the check engine light returns.
5. If the code changes to P0305, the ignition coil is faulty and must be replaced.
6. If the code remains P0306, the coil is likely good. Move on to the spark plug. Remove the plug from cylinder 6 and inspect it for wear, damage, or oil/carbon fouling. Check the spark plug well for any pooled oil, which indicates a valve cover gasket leak. Replace the plug if necessary.
7. If the plug and coil are good, the issue may be the fuel injector. This requires more advanced diagnosis, such as using a stethoscope to listen for the injector's clicking sound or performing a balance test.
8. If the vehicle is a 2.7L EcoBoost with a build date between April 2016 and Jan 2017, and it exhibits high oil consumption, refer to Ford TSBs 19-2243/19-2384 and have a professional perform a compression and leak-down test to check for internal engine damage.

Parts You'll Likely Need

• Ignition Coil (3.5L V6) (OEM #DG520 (7T4Z-12029-E)) — This is the most frequent cause of a P0306 misfire on the naturally aspirated 3.5L V6.
  Trusted brands: Motorcraft, NGK, Denso
  OEM price range: $60-$90
  Aftermarket price range: $35-$65
• Ignition Coil (2.7L EcoBoost V6) (OEM #DG555 (FT4Z-12029-A)) — This is the most frequent cause of a P0306 misfire on the 2.7L EcoBoost V6.
  Trusted brands: Motorcraft, Autopart Premium, Hitachi
  OEM price range: $50-$80
  Aftermarket price range: $30-$60
• Spark Plug (3.5L V6) (OEM #SP-589) — Worn spark plugs are the second most common cause. It is best practice to replace them when replacing a coil. SP-589 is a common Motorcraft plug for the 3.5L V6.
  Trusted brands: Motorcraft, NGK, Bosch
  OEM price range: $15-$25
  Aftermarket price range: $8-$18
• Spark Plug (2.7L EcoBoost V6) (OEM #SP-594 (CYFS-12Y-RT3)) — Worn or improperly gapped spark plugs are a common cause of misfires on EcoBoost engines. It's critical to use the correct plug and gap.
  Trusted brands: Motorcraft, NGK
  OEM price range: $12-$20
  Aftermarket price range: $7-$15

Related Codes That Often Appear With This One

• P0300 — This is a 'Random Misfire' code that often appears alongside a specific cylinder misfire code like P0306, especially if the issue is intermittent or beginning to affect other cylinders.
• P0316 — Indicates a misfire was detected within the first 1,000 engine revolutions after startup. It is often seen with other P030x codes and is specifically mentioned in the TSBs for the 2.7L engine issue.
• P0524 and P06DD — These codes, for low oil pressure, are specifically mentioned in Ford TSBs 19-2243 and 19-2384 alongside misfire codes when there is excessive oil consumption and potential internal engine damage on the 2.7L EcoBoost.
• P0356 — This code indicates a fault in the ignition coil primary/secondary circuit for cylinder 6. It points more directly to an electrical issue with the coil or its wiring and is a strong indicator of potential PCM damage on the 3.5L V6 if it persists after a coil swap.
• P0206 — This code indicates an issue with the fuel injector circuit for cylinder 6. If seen with P0306, it strongly suggests the fuel injector or its wiring is the culprit, not the ignition system.

Technical Service Bulletins (TSBs) & Recalls

• TSB 19-2243: Supersedes earlier bulletins, providing a detailed service procedure to replace the cylinder heads on affected 2016-2017 Edge/MKX and 2017 Fusion/MKZ with 2.7L/3.0L EcoBoost engines (built Apr 2016 - Jan 2017) to fix an oil consumption and misfire issue caused by valve guides.
• TSB 19-2384: Specifically addresses the 2.7L EcoBoost in the 2016-2017 F-150 for the same issue (oil consumption, rough idle, misfire DTCs P0300-P0306) with the same build date range, confirming the problem across platforms.
• SSM 54504: Notes that misfire DTCs P0300-P0306 can be associated with excessive oil consumption and other codes like P0524/P06DD.
• SSM 46363: Suggests suspecting the cylinder heads as the cause of misfires with oil consumption, and the long block if P0524/P06DD are also present.

Platform-Specific Known Issues

• 2.7L EcoBoost Engine Failure: Per TSBs 19-2243 and 19-2384, some 2016-2017 models with the 2.7L engine built from April 2016 through January 2017 may exhibit misfire codes (P0300-P0306) along with excessive oil consumption and white or blue exhaust smoke. The cause is identified as faulty valve guides, and the prescribed fix is to replace both cylinder heads. There are forum discussions where owners with these symptoms ultimately required a full engine replacement.
• 3.5L V6 PCM Failure: On V6 engines, a failing ignition coil can experience an internal short, sending a high-voltage spike back to the Powertrain Control Module (PCM) and damaging the internal driver circuit for that cylinder. This results in a persistent misfire code (P0306 or P0356) even after replacing the coil and plug, and requires a costly PCM replacement or repair.

Mechanic-Grade Diagnostic Values

• Spark Plug Gap (2.7L EcoBoost) — expected: 0.028 - 0.031 in (0.7 - 0.8 mm). Failure: An incorrect gap can lead to a weak or inconsistent spark, causing misfires under load.
• Low-Pressure Fuel System (All Engines) — expected: 40 - 75 PSI. Failure: Pressure below this range indicates a weak in-tank fuel pump, which can cause misfires on all cylinders, but may first appear on one.
• High-Pressure Fuel System (2.7L EcoBoost) — expected: 65 PSI (low demand) to over 2,150 PSI (high demand). Failure: A reading that doesn't respond to engine demand or a P0087 code suggests a failing High-Pressure Fuel Pump (HPFP), which can cause hesitation and misfires.

Hidden / Shadow Codes Worth Checking

• Mode 6, Test ID $0A, Component ID $06: This is not a DTC, but a specific data parameter accessible with advanced scan tools. It shows the raw misfire count for cylinder 6 for the current and last ten driving cycles. (see via A scan tool with Mode 6 capabilities. A high count confirms the misfire is consistently on cylinder 6, even if the CEL is not flashing.)

Scan Tool Commands That Help

• Ford IDS (or equivalent professional scanner): Power Balance Test — This is a critical diagnostic step. The test disables one cylinder at a time and measures the RPM drop. If disabling cylinder 6 results in little or no RPM drop compared to other cylinders, it confirms that cylinder 6 is not contributing power, pinpointing the misfire without a test drive.
• Ford IDS (or equivalent professional scanner): Injector Flow Test — If spark and compression are confirmed to be good, this function can be used to command the fuel injector for cylinder 6 to operate and measure the corresponding pressure drop in the fuel rail, helping to identify a clogged or failing injector.

Wiring & Ground Locations

• PCM Power Relay — In the under-hood fuse box (Power Distribution Box).. This relay supplies power to the PCM. A faulty relay can cause a host of issues, including no-start or intermittent stalling, which could be misdiagnosed as a specific component failure. The PCM controls the ground for this relay.
• PCM Main Grounds — On the 2.0L EcoBoost (similar architecture), main PCM grounds are located at a single point. On V6 models, look for ground straps from the engine block to the firewall and chassis.. A poor ground connection for the PCM can cause erratic behavior, including misfire codes. The PCM relies on a solid ground to accurately control the ignition coils and fuel injectors.
• Cylinder 6 Coil Driver Wire — Runs from a specific pin on the main PCM connector (e.g., C175E on some Ford models) to the ignition coil connector for cylinder 6.. If a P0356 code is present, it indicates a fault in this specific circuit. A technician would test for continuity and shorts on this wire between the PCM and the coil to rule out a wiring issue before condemning the PCM.
• Battery Location — Behind the front passenger-side wheel well, accessible by removing the splash shield.. Technicians performing electrical diagnosis need to know the battery is not under the hood. Accessing it requires removing the wheel and splash shield, which is important for estimating labor time for any tests requiring a direct battery connection or disconnection.

Real Owner Repair Stories

• Ford Edge Forum (Ford Edge with 3.5L V6) — Rough running, Check Engine Light with codes P0206 (Injector Circuit/Open Cylinder 6) and P0306 (Cylinder 6 Misfire).
  ❌ Tried (didn't work) Initial diagnosis pointed towards common ignition or wiring issues.
  ✅ What actually fixed it The user suspected the fuel injector for cylinder #6 was getting stuck when hot. The problem was intermittent and seemed to occur after the engine reached operating temperature. Replacing the fuel injector resolved both codes.

OEM Part Supersession History

• SP520A → SP589 — The SP589 is a newer version of the Motorcraft spark plug recommended for the 3.5L V6.
  Heads up: Both are compatible, but SP589 is the current recommended replacement part.
• 7T4Z-12029-DA → DG520 (7T4Z-12029-E) — DG520 is the updated Motorcraft part number for the ignition coil on many 3.5L V6 applications.
  Heads up: Multiple aftermarket interchange part numbers exist (UF553, UF595), but using the OEM Motorcraft part is highly recommended to avoid compatibility issues and premature failure.