P0316 on 2019-2025 Ford Ranger: Startup Misfire Causes and Fixes

What's Unique About the 2019-2025 Ford Ranger

The 2019-2025 Ford Ranger with the 2.3L EcoBoost engine is uniquely prone to this issue due to a design characteristic. A seam in the cowl panel above the engine can allow water from the windshield to drip directly onto the engine, especially when parked nose-down. On models without a protective engine cover (a part Ford reportedly deleted on some trims after the 2019 model year), this water pools in the spark plug wells. This causes the ignition coils and spark plugs to corrode, leading directly to startup misfires. This well-documented issue is the subject of several Ford Technical Service Bulletins, including TSB 23-2011.

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 (solid or flashing)
• Rough or shaky idle, especially right after starting the engine
• Engine hesitation or stumbling during acceleration
• Noticeable lack of power
• Difficulty starting the engine in some cases
• Engine vibration is more pronounced on a cold start
🎬 Watch: How to diagnose and fix a P0316 startup misfire code.

Most Likely Causes

1. Water Intrusion in Spark Plug Wells 🔴 High Probability → Shop Spark Plug As detailed in Ford TSB 23-2011, the cowl design allows water to drip onto the engine, and the absence of an engine cover on post-2019 models leaves the spark plug wells exposed. Forum users on The Ranger Station and other communities widely corroborate this, noting it's worse when parked facing downhill.
   How to confirm: Remove the ignition coils and visually inspect the spark plug wells. Look for standing water, rust-colored stains on the coil boots and cylinder head, or white, chalky corrosion on the coils and spark plugs.
   Typical fix: Dry out the spark plug wells completely using compressed air. 🎬 See a quick trick for removing liquid from spark plug wells. Replace any corroded ignition coils and all four spark plugs. Apply a liberal amount of dielectric grease (like Permatex 22058) to the inside of the new ignition coil boots to seal them against future moisture. Install the updated engine cover (Part #L1MZ-6A949-A or newer #L1MZ-6A949-C) and the required mounting studs (Part #W714647-S450B, quantity 2) and nuts (Part #W520201-S450B, quantity 2) to prevent recurrence.
   Est. part cost: $150-$400
2. Worn or Fouled Spark Plugs 🟡 Medium Probability → Shop Spark Plug While Ford specifies a 100,000-mile interval, the high-pressure, direct-injection EcoBoost engine is sensitive to spark quality. Plugs can wear out sooner, and the water intrusion issue dramatically accelerates fouling and corrosion. Even without water, the gap can wear beyond spec. The correct gap is 0.028-0.031 inches (0.7-0.8 mm).
   How to confirm: Remove the spark plugs. Inspect for a worn electrode, carbon fouling, oil contamination, or corrosion. Measure the gap with a feeler gauge. The OEM plug SP-578 was superseded by SP-594. Even if they look clean, they may be the cause if they have high mileage.
   Typical fix: Replace all four spark plugs. It is recommended to use high-quality Iridium plugs like Motorcraft SP-594. Torque new plugs to 106 in-lbs (8 ft-lbs).
   Est. part cost: $40-$80
3. Faulty Ignition Coil(s) 🟡 Medium Probability → Shop Ignition Coil Ignition coils are a common failure item, but their lifespan is significantly shortened by the water intrusion issue on this specific truck. Corrosion on the coil spring and boot is the primary mode of failure.
   How to confirm: If a specific cylinder misfire code (e.g., P0302) is present, swap the ignition coil from that cylinder with one from a known good cylinder. Clear the codes and see if the misfire code follows the coil to the new cylinder. Visually inspect the coil for white or rust-colored corrosion.
   Typical fix: Replace the faulty ignition coil. It is strongly recommended to replace all four coils at the same time, especially if they have been exposed to moisture, to ensure reliability.
   Est. part cost: $50-$100 per coil

Rare But Worth Checking

• Cold Soak Misfire (Software Related): TSB #SSM 54451 mentions a specific condition on 2.3L EcoBoost engines where codes P0300 and P0316 may appear after a cold soak without other cylinder-specific misfires. This could point to a nuanced issue, potentially requiring a PCM software update from a dealer.
• Leaking Fuel Injector: → Shop Fuel Injector A fuel injector that leaks slightly when the engine is off can cause a rich misfire on startup. This is less common than ignition-related issues but is a possibility, as noted in forums for other EcoBoost vehicles with similar codes.
• Low Fuel Quality or Fuel Blend Changeover: Sometimes, a switch between summer and winter fuel blends or a tank of poor-quality fuel can cause a temporary startup misfire that sets a P0316 code, often with no other symptoms. If the code appears alone, it may resolve on its own after a few tanks of fresh, high-quality fuel.
• Community-Identified Cowl Seam Fix: As an alternative or supplement to the engine cover, some owners on forums like The Ranger Station have successfully prevented water intrusion by sealing the cowl seam at the base of the windshield with foam pipe insulation or silicone sealant.

Diagnosis Steps

1. Read all stored DTCs with an OBD-II scanner. Note any accompanying codes like P0300 or P0301-P0304, which will help isolate the problem cylinder(s).
2. Visually inspect the area at the base of the windshield (the cowl) for a seam that might be leaking water onto the engine. Note if the truck is parked on an incline, as this can worsen the leak.
3. Remove the plastic engine vanity cover if present. If not present, this increases the likelihood of water intrusion, as this part was deleted on many trucks after 2019.
4. Remove the 8mm bolts holding the ignition coils. Start with the cylinder indicated by the trouble code (e.g., Cylinder 4 for P0304). If only P0300/P0316 are present, inspect all four, paying close attention to the rearmost cylinders which are often most affected.
5. Carefully inspect the spark plug well for any standing water, rust-colored stains, or white corrosion on the ignition coil boot and the top of the spark plug.
6. If water/corrosion is found, the cause is confirmed. Use compressed air to blow out all debris and moisture from the wells. Proceed to replace all four spark plugs and any visibly corroded ignition coils.
7. If no water is present, check the spark plug gap (spec is 0.028-0.031 in). If plugs are good, proceed with standard misfire diagnostics: swap ignition coils to see if the misfire follows, and check fuel injector function if necessary.
8. After repairs, apply dielectric grease to the new coil boots and install the Ford engine cover kit (Cover L1MZ-6A949-C, Studs W714647-S450B, Nuts W520201-S450B) to prevent future water intrusion. 🎬 Watch: Step-by-step guide to installing the Ford engine cover kit. Torque the cover stud bolts and nuts to 89 lb-in (10 Nm).

Parts You'll Likely Need

• Ignition Coil (OEM #DG-576) — These are often damaged by the water that pools in the spark plug wells, causing corrosion and failure.
  Trusted brands: Motorcraft
  OEM price range: $80-$95
  Aftermarket price range: $40-$70
• Spark Plugs (OEM #SP-594) — Required for any tune-up and are the final point of failure in a misfire. They are often corroded along with the coils due to water intrusion. This part number supersedes the original SP-578.
  Trusted brands: Motorcraft, NGK
  OEM price range: $10-$15 per plug
  Aftermarket price range: $8-$12 per plug
• Engine Appearance Cover Kit (OEM #L1MZ-6A949-A (or L1MZ-6A949-C)) — This is Ford's official fix to shield the spark plug wells from water dripping from the cowl seam. It was omitted on some models after 2019. Installation requires additional hardware.
  Trusted brands: Motorcraft
  OEM price range: $50-$95
  Aftermarket price range: N/A
• Engine Cover Mounting Hardware (OEM #Studs: W714647-S450B (x2), Nuts: W520201-S450B (x2)) — These studs and nuts are required to install the engine cover on vehicles that did not come with one from the factory.

Related Codes That Often Appear With This One

• P0300 — This indicates a random or multiple cylinder misfire, which is common when water affects more than one spark plug well.
• P0301, P0302, P0303, P0304 — These codes pinpoint the specific cylinder(s) that are misfiring along with the P0316 startup detection. For example, P0301 is a misfire in Cylinder 1.

Technical Service Bulletins (TSBs) & Recalls

• TSB 23-2011: The most comprehensive TSB, which outlines the misfire DTCs (including P0316), confirms the cause as water in spark plug wells, and instructs technicians to resolve the misfire and install an engine appearance cover.
• SSM 51051 / SSM 51239: Earlier service messages that also identify the water intrusion issue on 2019-2022 Rangers, leading to corrosion and misfire DTCs.
• SSM 54451: Mentions P0300 and P0316 occurring after a cold soak without other cylinder-specific misfires, suggesting a potential software-related condition in some cases.

Platform-Specific Known Issues

• A series of Technical Service Bulletins (TSBs), including #SSM 51051, #SSM 51239, and most notably #TSB 23-2011, have been issued by Ford regarding P0316 and other misfire codes on 2019-2022 Rangers. They all point to water buildup in the spark plug wells causing corrosion on ignition components.
• Forum discussions among owners on platforms like ranger5g.com and TheRangerStation.com confirm that water intrusion is a widespread problem, often caused by a cowl seam leak, and that installing the engine cover is the recommended preventative measure.

Mechanic-Grade Diagnostic Values

• Ignition Coil Primary Resistance — expected: Under 5.0 ohms. Failure: A reading higher than 5.0 ohms or an open circuit indicates a faulty coil.
• Ignition Coil Hold-Down Bolt Torque — expected: 62-71 in-lbs (7-8 Nm). Failure: Over-torquing can damage the coil or valve cover; under-torquing can allow the coil to vibrate loose.
• High-Pressure Fuel System (HPFP) Maximum Operating Pressure — expected: Stock system operates at high pressure; aftermarket systems are rated for up to 250 bar / 3626 psi.. Failure: Low fuel pressure is a potential cause of misfires, though specific stock values require a dedicated scan tool to monitor.

Hidden / Shadow Codes Worth Checking

• Mode 6, Test ID $A2-$AF: Provides misfire counts for each cylinder (e.g., Test ID $A3 for Cylinder 2) during the current or last drive cycle. This can reveal intermittent or low-frequency misfires that haven't yet triggered a P030x code. (see via A professional OBD-II scan tool with Mode 6 data capability. The data is presented as raw counts and must be compared against a manufacturer-defined limit.)

Scan Tool Commands That Help

• Ford IDS, Snap-on, Autel, or other professional scanner: Power Balance Test — Used to identify a weak or non-contributing cylinder when misfire codes are present but the specific cylinder is unknown (P0300/P0316), or to confirm a suspected cylinder. The tool deactivates one cylinder at a time and graphs the RPM drop; a cylinder with little to no RPM drop is faulty.
• Ford IDS or advanced bidirectional scanner: Crankshaft Position System Variation Relearn — This procedure is required after replacing the crankshaft position sensor (CKP) or the PCM. It calibrates the PCM to the minor variations of the new sensor. Failure to perform this can sometimes lead to misfire detection issues and codes like P0316 or P0315.

Real Owner Repair Stories

• Reddit user in r/MechanicAdvice (Ford Ranger (older V6 model, but same P0316/P0301 codes)) — Rough/bumpy idle, P0316 and P0301 codes.
  ❌ Tried (didn't work) User suspected wiring harness issues that had been previously replaced.
  ✅ What actually fixed it Replacing only the ignition coil pack resolved the issue. The spark plugs and wires had been replaced less than a year prior.
• Reddit user in r/fordranger (2004 Ford Ranger FX4 (older model, demonstrates alternative causes)) — P0316, P0300, and multiple specific cylinder misfire codes (P0303, P0304, P0305, P0306), rough idle, heavy white smoke from exhaust.
  ❌ Tried (didn't work) Cleaning oil-fouled spark plugs.
  ✅ What actually fixed it The issue was not fully resolved by the user, but diagnosis revealed the root cause was severe internal engine problems. A compression test on cylinder 6 showed only 60 PSI, indicating a failure of piston rings or valves. This serves as a crucial counter-example to common ignition-related fixes.

When the Usual Fixes Don't Work

• While the most common cause of P0316 on the 2019-2025 Ranger is water intrusion into the spark plug wells, this is not the only possibility. If the standard fix of replacing coils, plugs, and adding the engine cover does not resolve the issue, more serious mechanical problems should be investigated. In one documented case involving similar codes, an owner discovered oil-fouled spark plugs which led to a compression test. The test revealed a cylinder with very low compression (60 PSI), pointing to a significant internal engine failure like bad piston rings or valve issues, a much more complex and expensive repair than the common water leak fix. This highlights the importance of performing deeper diagnostics if the initial, common fix does not work.

OEM Part Supersession History

• L1MZ-6A949-A → L1MZ-6A949-C — Updated design for the engine appearance cover, which is the primary fix for the water intrusion issue.
• Motorcraft SP-578 → Motorcraft SP-594 — Updated spark plug design.
• JX6Z12029A, JX6Z12029B → Motorcraft DG-576 (OEM equivalent) — Part number evolution for the ignition coil.
  Heads up: Aftermarket equivalent often listed as UF855.

Model Year Variations Within This Range

• 2020-2025 (Primarily non-Lariat trims): Many models produced after the 2019 model year did not include the engine appearance cover from the factory. This omission is the primary reason the water intrusion issue is so prevalent on these model years, as the cover acts as a shield for the spark plug wells.