P0305 on 2017 Lincoln Continental: Cylinder 5 Misfire Causes and Fixes

What's Unique About the 2017-2017 Lincoln CONTINENTAL

For the 2.7L and 3.0L twin-turbo (EcoBoost) engines, this is not a typical misfire code. Multiple manufacturer TSBs, most notably TSB 19-2243, point to a significant internal engine problem where faulty valve guides lead to excessive oil consumption and misfires. This means a simple tune-up part like a spark plug or ignition coil may not fix the issue; the root cause is often a major mechanical failure requiring cylinder head replacement as documented by Ford/Lincoln.

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 shaking idle.
• Engine hesitation or stumbling during acceleration.
• Noticeable loss of power.
• Flashing or solid Check Engine Light.
• Smell of fuel from the exhaust.
• Excessive oil consumption (specific to 2.7L/3.0L engines), defined as 1 quart in less than 3,000 miles.
• White or blue smoke from the exhaust, especially after a hot restart (specific to 2.7L/3.0L engines).

Most Likely Causes

1. Internal Engine Defect (2.7L & 3.0L Twin-Turbo Engines) 🔴 High Probability A known issue documented in TSB 19-2243 affects vehicles built from April 1, 2016, to January 1, 2017, where faulty valve guides cause excessive oil consumption, fouling spark plugs and leading to misfires. This is a widely discussed topic in owner forums for affected vehicles.
   How to confirm: Monitor oil consumption; an oil loss of 1 quart in under 3,000 miles is the key indicator specified in the TSB. A professional should perform a cylinder compression test and/or a leak-down test to confirm internal failure. The presence of codes P0524 or P06DD alongside the misfire code strongly points to this issue.
   Typical fix: Replacement of both left and right cylinder heads and associated gaskets, as specified in TSB 19-2243. In some earlier versions of the TSB, or if low oil pressure codes were present, a complete engine long block replacement was recommended.
   Est. part cost: $1500-$3000+
2. Faulty Ignition Coil 🟡 Medium Probability → Shop Ignition Coil Coil-on-plug systems are a common failure point on most modern vehicles due to heat and vibration. This is a more likely cause on the 3.7L V6 engine, which is not affected by the cylinder head TSB.
   How to confirm: Swap the ignition coil from cylinder 5 with another cylinder (e.g., cylinder 4). Clear the codes and drive. If the code changes to P0304, the coil is faulty.
   Typical fix: Replace the single faulty ignition coil. It is often recommended to replace all coils if they are original and high-mileage.
   Est. part cost: $40-$80
3. Worn or Fouled Spark Plug 🟡 Medium Probability → Shop Spark Plug Spark plugs are a regular maintenance item. On the turbo engines, oil consumption from the TSB issue can quickly foul the spark plug, causing a misfire. Direct injection engines are also prone to carbon buildup which can affect the plug.
   How to confirm: Remove the spark plug from cylinder 5 and inspect it for wear, carbon buildup, or oil fouling. Compare it to a new plug. An oil-soaked plug on a 2.7L/3.0L engine is a strong sign of the TSB issue.
   Typical fix: Replace the spark plug. If it is oil-fouled on a turbo engine, the root cause (cylinder head) must be addressed. It is best practice to replace all six spark plugs at the same time.
   Est. part cost: $10-$25 per plug
4. Clogged or Faulty Fuel Injector ⚪ Low Probability → Shop Fuel Injector
   How to confirm: A professional can test the fuel injector's flow rate and electrical function. A DIY method is to listen for a consistent 'clicking' sound from the injector using a mechanic's stethoscope. You can also swap the injector with another cylinder, similar to the ignition coil test, though this is more labor-intensive.
   Typical fix: Replace the faulty fuel injector.
   Est. part cost: $70-$150

Rare But Worth Checking

• Vacuum Leak: A leak in the intake manifold gasket or a vacuum hose near cylinder 5 could lean out the air-fuel mixture, causing a misfire.
• PCM Driver Circuit Failure: In rare cases, the electronic driver within the Powertrain Control Module (PCM) that fires the ignition coil can fail, mimicking a bad coil. This requires 🎬 Watch: Diagnosing intermittent misfires on a 2017 EcoBoost engine. advanced diagnostics to confirm.
• Wiring Harness Issues: Ford has issued TSBs like SSM 47791 for this platform regarding wiring damage between harness connectors (C1016 and C1168), which can cause various sensor faults. While not directly for P0305, it highlights a known vulnerability in the engine wiring harness that could potentially affect an ignition coil or injector circuit.

Diagnosis Steps

1. Read all stored fault codes with an OBD-II scanner. Note any 🎬 See how to perform a power balance test with a scanner. codes accompanying P0305, especially P0524 or P06DD, as this strongly suggests the major TSB issue on 2.7L/3.0L engines.
2. Check the engine oil level. If it is low, especially on a 2.7L or 3.0L model, suspect the TSB-related issue and begin an oil consumption test.
3. Perform a basic visual inspection of the engine bay, looking for obvious issues like a disconnected vacuum hose or damaged wiring near cylinder 5 (front bank, middle cylinder).
4. To isolate a spark issue, swap the ignition coil from cylinder 5 with an adjacent cylinder (e.g., cylinder 4). Clear the codes and drive the vehicle to see if the misfire code returns and if it has moved to the other cylinder (e.g., P0304). If it moves, the ignition coil is bad.
5. If the code does not move, swap the spark plug from cylinder 5 to another cylinder. If the code follows the plug, the plug is bad.
6. While the spark plug from cylinder 5 is out, inspect it. Look for signs of wear, damage, or heavy oil fouling. A wet, oily plug on a 2.7L/3.0L engine is a major red flag for the internal engine defect.
7. If the plug is oil-fouled and the engine is a 2.7L/3.0L, refer to TSB 19-2243. The vehicle needs professional diagnosis, including a compression and leak-down test, to confirm the need for cylinder head replacement.
8. If spark and compression are good, the issue may be with the fuel injector, which requires more advanced testing, such as a flow test or swapping its position with another cylinder's injector.

Parts You'll Likely Need

• Cylinder Head Assembly (OEM #GB8Z-6049-G (Left), GB8Z-6049-F (Right) for 3.0L) — This is the specific fix for the known TSB 19-2243 issue on 2.7L/3.0L EcoBoost engines causing oil consumption and misfires.
  Trusted brands: Motorcraft
  OEM price range: $1000-$1500 per head
  Aftermarket price range: $700-$1200 per head
• Ignition Coil (OEM #FT4Z-12029-A (for 2.7L/3.0L)) — A common failure point for misfires when the TSB issue is not the cause, especially on the 3.7L engine.
  Trusted brands: Motorcraft, NGK, Denso
  OEM price range: $60-$90
  Aftermarket price range: $40-$70
• Spark Plug (OEM #SP-594 (for 2.7L/3.0L)) — A standard maintenance part that can wear out or become fouled by oil due to the TSB issue. The correct plug for the EcoBoost engines is an Iridium type.
  Trusted brands: Motorcraft, NGK
  OEM price range: $15-$25
  Aftermarket price range: $10-$20

Related Codes That Often Appear With This One

• P0300 — Indicates random, multiple misfires. If the underlying cause (like the TSB issue) affects more than one cylinder, P0300 may appear with P0305.
• P0301, P0302, P0303, P0304, P0306 — These codes indicate misfires in other cylinders, pointing to a systemic problem rather 🎬 Watch: Troubleshooting tips for multiple EcoBoost misfire codes. than a single component failure.
• P0524 — Stands for 'Engine Oil Pressure Too Low'. This code is specifically mentioned in the TSBs and is a strong indicator of the severe internal engine problem when seen with misfire codes.
• P06DD — Stands for 'Engine Oil Pressure Control Circuit Stuck Off'. Like P0524, this code is cited in the TSBs and points towards the serious oil-related engine failure.

Technical Service Bulletins (TSBs) & Recalls

• TSB 19-2243: Supersedes earlier versions. Provides the most detail on the 2.7L/3.0L EcoBoost oil consumption/misfire issue. Specifies build dates (Apr 2016 - Jan 2017) and confirms the fix is cylinder head replacement.
• SSM 54504: Mentions misfire codes with excessive oil consumption and other DTCs like P0524/P06DD, pointing towards the same internal engine issue.
• SSM 46364: An earlier bulletin linking misfire codes and oil consumption to cylinder heads or the long block, corroborating the severity of the problem.

Platform-Specific Known Issues

• TSB 19-2243 (which supersedes TSB 17-2235) and SSM 54504 identify a significant issue on some 2017 Continentals with the 2.7L and 3.0L EcoBoost engines built between April 1, 2016 and January 1, 2017. The problem stems from defective valve guides, leading to excessive oil consumption (1qt/3000mi), which in turn causes misfires and can trigger codes P0300-P0306, P0524, and P06DD. The official repair is a complete replacement of the cylinder heads, a job estimated by Ford at over 25 hours.

Mechanic-Grade Diagnostic Values

• Ignition Coil Primary Resistance — expected: 0.52 - 0.64 Ohms. Failure: A reading outside of this range, or an open circuit (OL), indicates a faulty coil.
• Ignition Coil Secondary Resistance — expected: 6,600 - 7,900 Ohms (6.6 - 7.9 kOhms). Failure: A reading outside of this range suggests a failure in the coil's secondary windings.
• Mode $06 Misfire Count (Cylinder 5) — expected: 0. Failure: A non-zero value indicates the number of misfire events detected on cylinder 5 during the current and previous ten driving cycles, even if not enough to set a CEL.

Hidden / Shadow Codes Worth Checking

• Mode $06, TID $81, CID $05: This is not a DTC but a specific monitor within the generic OBD-II functions. It tracks the raw misfire count for cylinder 5. It is invaluable for detecting intermittent misfires that haven't yet reached the threshold to trigger a P0305 code. (see via Requires a scan tool capable of displaying Mode $06 data, such as FORScan or a professional-grade scanner.)

Scan Tool Commands That Help

• Ford IDS / FORScan: Power Balance Test — This is a critical diagnostic function for misfires. The tool displays a real-time graph of the power contribution from each cylinder. A cylinder with a misfire will show a significant drop compared to the others, instantly confirming the location of the issue without swapping parts. The technician can also selectively disable injectors to see the effect on the engine.
• FORScan: Live Data PID: NUM_MISFIRE — This PID (Parameter ID) shows a cumulative count of all misfires across all cylinders. If this number is actively increasing while driving or idling, it confirms a current misfire condition. This can be monitored alongside individual cylinder misfire PIDs to see if the problem is isolated or random.

Wiring & Ground Locations

• G102 — Located at the left rear of the engine.. This is the designated ground point for all eight ignition coils on some Ford V8 engines, and similar logic applies to the V6. A loose or corroded connection at this single point can cause erratic behavior, including misfires, on multiple cylinders that might be difficult to diagnose.
• PCM Connector C1551E, Pin 58 — This is one of the main connectors on the Powertrain Control Module (PCM).. Pin 58 is the specific control wire (driver) for the cylinder 5 ignition coil on some Ford V6 engines. A technician can test for a square wave signal at this pin to determine if the PCM is commanding the coil to fire. A lack of signal points to a PCM or wiring issue, while a good signal with a misfire points to a problem with the coil, plug, or harness.

Real Owner Repair Stories

• lincolncontinentalforum.com user (2017 Lincoln Continental 3.0T AWD) — Check engine light with P0305, excessive oil consumption.
  ❌ Tried (didn't work) Initial diagnosis focused on standard tune-up parts.
  ✅ What actually fixed it The owner took the vehicle to a Lincoln dealer who confirmed the issue was related to TSB 19-2243. The dealer replaced both cylinder heads under warranty, which resolved both the oil consumption and the P0305 misfire code.

OEM Part Supersession History

• Unknown (Original-fitment cylinder heads on vehicles built Apr 2016 - Jan 2017) → GB8Z-6049-G (Left) and GB8Z-6049-F (Right) for 3.0L engines. — To correct the excessive oil consumption issue caused by defective valve guides as documented in TSB 19-2243.
  Heads up: Using old stock or salvaged cylinder heads from the affected production range will not solve the problem.

Model Year Variations Within This Range

• 2017 models built between April 1, 2016, and January 1, 2017: Vehicles within this build date range equipped with the 2.7L or 3.0L EcoBoost engines are susceptible to the cylinder head valve guide defect outlined in TSB 19-2243. Vehicles built after this date have the updated cylinder head design from the factory and are not prone to this specific cause of P0305.