P0025 on 2015-2016 Lincoln MKS: Exhaust Camshaft Timing Causes and Fixes

What's Unique About the 2015-2016 Lincoln MKS

For this generation of Lincoln MKS and its related Ford platforms, the VCT system is known to be sensitive to oil quality. Ford/Lincoln has issued Technical Service Bulletins (specifically TSB SSM 50067) acknowledging that P0025 can be caused by small debris in the oil causing the VCT solenoid to stick. This makes regular oil changes with the manufacturer-specified oil viscosity particularly crucial. Furthermore, the 3.5L engine variant has a timing-chain-driven internal water pump; a failure of this pump can contaminate the engine oil with coolant, leading to accelerated wear on timing components and causing VCT-related codes like P0025 as a secondary, more severe symptom.

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
• Rough or unstable idle
• Reduced engine power and poor acceleration
• Decreased fuel economy
• Engine may be hard to start
• Engine stalling, especially when coming to a stop
• Engine may have ticking or knocking noises

Most Likely Causes

1. Low, Dirty, or Incorrect Viscosity Engine Oil 🔴 High Probability The VCT system is hydraulic and highly sensitive to oil pressure and cleanliness. TSB SSM 50067 directly links oil debris to sticking solenoids, and this is the most common trigger for the fault.
   How to confirm: Check the oil level on the dipstick and inspect its color and consistency. If it's low, dark, or sludgy, it needs to be changed. This should always be the first step.
   Typical fix: Perform an oil and filter change using the manufacturer-specified full synthetic grade of oil and a quality filter (e.g., Motorcraft).
   Est. part cost: $40-$80
2. Failing or Sticking Bank 2 Exhaust VCT Solenoid 🔴 High Probability → Shop Engine Variable Valve Timing (VVT) Solenoid This is a widely documented failure point on Ford/Lincoln V6 engines, as noted in TSB SSM 50067, which states debris can cause the solenoid to stick. It is the most common failed component for this code.
   How to confirm: After confirming oil level is correct, a mechanic can use a scan tool to command the solenoid on and off 🎬 See this guide on how to tell if your solenoid is bad. to check for response. TSB SSM 50067 suggests cycling the solenoid 10 times to try and clear debris before replacement. A useful DIY test is to swap the Bank 2 exhaust solenoid with the Bank 2 intake solenoid; if the code changes to P0021 or P0022, the solenoid is confirmed faulty.
   Typical fix: Replace the Bank 2 (radiator side) exhaust VCT solenoid and its seal.
   Est. part cost: $40-$100
3. Worn Timing Components (Cam Phaser, Timing Chain, Guides) ⚪ Low Probability While less common than oil or solenoid issues, wear on mechanical timing parts can occur at higher mileage. On 3.5L engines, this is often accelerated by a failing internal water pump leaking coolant into the oil.
   How to confirm: This is a more involved diagnosis. Listen for a distinct rattling or ticking noise on cold startups, which is a classic symptom of phaser or chain wear. A mechanic would need to remove the valve cover and potentially the timing cover to inspect the components for wear, damage, or slack.
   Typical fix: Replace the worn timing components (phasers, chain, guides, tensioners). This is a significant, labor-intensive repair.
   Est. part cost: $400-$1200
4. Wiring or Connector Issue at VCT Solenoid ⚪ Low Probability → Shop Engine Variable Valve Timing (VVT) Solenoid
   How to confirm: Visually inspect the wiring harness and connector for the Bank 2 exhaust VCT solenoid for any signs of damage, corrosion, oil contamination, or loose pins. Perform a wiggle test on the connector while the engine is running to see if it affects idle.
   Typical fix: Repair the damaged wiring or replace the connector pigtail.
   Est. part cost: $15-$50

Rare But Worth Checking

• Clogged Oil Passages: If an engine has a history of infrequent oil changes, sludge can build up and block the small oil passages leading to the VCT components, even if the solenoid itself is functional. This requires extensive engine cleaning.
• Failing Powertrain Control Module (PCM): This is extremely rare. The PCM should only be considered after all other possibilities, including mechanical and electrical, have been exhaustively ruled out by a professional.

Diagnosis Steps

1. Check Engine Oil: Verify the engine oil level is correct and the oil is clean. If low, dirty, or past its service interval, perform an oil and filter change with the correct viscosity oil (e.g., 5W-20 or 5W-30 full synthetic, check owner's manual). Clear the code and see if it returns.
2. Inspect VCT Solenoid Wiring: Visually inspect the electrical connector and wiring for the Bank 2 exhaust VCT solenoid (on the radiator-side valve cover) for any damage, corrosion, or loose connections.
3. Scan Tool Test: Use a capable scan tool to monitor the desired vs. actual camshaft position for the Bank 2 exhaust cam. Command the solenoid on and off to see if the timing angle changes as expected. The error PID should be near zero at hot idle.
4. Follow TSB Procedure: As per TSB SSM 50067, use the scan tool to cycle the suspect VCT solenoid 10 times to attempt to dislodge any debris before deciding to replace it.
5. Swap Solenoids (Diagnostic Trick): The intake and exhaust VCT solenoids on the same bank are often identical. Swap the Bank 2 exhaust solenoid with the Bank 2 intake solenoid. Clear the codes and drive the vehicle. If the code changes to P0021 or P0022 (intake cam codes), you have definitively confirmed the solenoid is the faulty part.
6. Test/Replace VCT Solenoid: If the solenoid fails the scan tool test, the swap test, or if the code returns, replace the Bank 2 exhaust VCT solenoid. 🎬 Watch: Step-by-step walkthrough for replacing the exhaust VCT solenoid. It is critical to also replace the solenoid seal and the valve cover gasket at the same time.
7. Check Mechanical Timing: If the problem persists after replacing the solenoid, the issue is likely mechanical. This requires a more in-depth inspection of the timing chain, tensioners, and cam phaser for wear or failure. This step is best left to a professional.

Parts You'll Likely Need

• Variable Camshaft Timing (VCT) Solenoid (OEM #AT4Z-6M280-B) — This solenoid is the most common point of failure for code P0025 on this vehicle, often getting stuck due to oil debris, as acknowledged in manufacturer TSBs.
  Trusted brands: Motorcraft, Dorman, SKP
  OEM price range: $70-$120
  Aftermarket price range: $40-$80
• Valve Cover Gasket Set (OEM #DL3Z-6584-C (example, verify for specific engine)) — Accessing the VCT solenoids on the 3.7L/3.5L V6 requires removing the valve cover. The gasket set (including spark plug tube seals) should always be replaced to prevent oil leaks.
  Trusted brands: Fel-Pro, Mahle, Motorcraft
  OEM price range: $40-$60
  Aftermarket price range: $20-$40
• VCT Solenoid Seal (OEM #BR3Z-6C535-A (verify fitment)) — This small seal fits on the VCT solenoid itself. It is crucial to replace this seal when replacing the solenoid to prevent oil from leaking past the solenoid into the valve cover area. It is often sold separately from the solenoid.
  Trusted brands: Motorcraft
  OEM price range: $5-$15
  Aftermarket price range: $3-$10

Related Codes That Often Appear With This One

• P0019 — This code indicates a Crankshaft/Camshaft correlation error for the same bank and camshaft. If the cam timing is over-retarded (P0025), its position relative to the crankshaft will also be incorrect.
• P0015 — This is the same over-retarded timing error but for Bank 1 (firewall side). Seeing both codes together could point to a systemic issue like very low oil pressure or widespread sludge affecting both VCT systems.
• P0024 — This is an over-advanced code for the same camshaft. Seeing P0025 and P0024 intermittently can point to an erratic VCT solenoid or an oil flow problem that is causing unpredictable movement.

Technical Service Bulletins (TSBs) & Recalls

• SSM 50067: VCT solenoid may be sticking due to small debris.
• SSM 54366: Diagnostic procedure (Pinpoint Test HK) has been updated for VCT codes.

Platform-Specific Known Issues

• TSB SSM 50067: Notes that P0025 (and other related VCT codes) may be caused by small debris causing the VCT solenoid to stick. It advises against immediate component replacement and instead recommends a diagnostic procedure (pinpoint test HK12) to try and clear the solenoid first by cycling it 10 times with a scan tool.
• TSB SSM 54366: Mentions that the diagnostic pinpoint test (Test HK) in the official workshop manual has been updated for this and other VCT-related trouble codes, indicating a refinement in the official diagnostic procedure.

Mechanic-Grade Diagnostic Values

• VCT Solenoid Internal Resistance — expected: 6.9 to 7.9 Ohms at 68°F (20°C).. Failure: A reading of 0 ohms (short circuit) or OL/infinite ohms (open circuit) indicates a failed solenoid.
• VCT Solenoid Connector Voltage (Key On, Engine Off) — expected: One pin should have battery voltage (~12.6V).. Failure: Low or no voltage points to a wiring issue, fuse, or PCM power relay problem, not the solenoid itself.
• Scan Tool VCT Cam Error PID (Ford IDS/FORScan) — expected: The error PID (e.g., VCT_EXH_ERR, VCT2ERR, VCT_ADV_ERR) should be near 0 degrees at hot idle.. Failure: The value is consistently off by more than a few degrees, or swings wildly, indicating the cam is not where the PCM is commanding it to be.
• Engine Oil Pressure at Hot Idle — expected: Minimum of 15 PSI.. Failure: Pressure below the minimum threshold can cause the VCT system to malfunction, even if all components are good.

Scan Tool Commands That Help

• Ford IDS (or equivalent professional scanner): VCT Solenoid Cycle Test (part of Pinpoint Test HK) — As per TSB SSM 50067, this command cycles the solenoid on and off 10 times to attempt to dislodge small debris that may be causing it to stick. This should be performed before replacing the solenoid.

Wiring & Ground Locations

• Bank 2 Exhaust VCT Solenoid Connector — On the Bank 2 (radiator side) valve cover, connecting to the top of the exhaust VCT solenoid.. The connector has two pins. One receives battery voltage (power) and the other is a ground signal controlled by the PCM to actuate the solenoid. Verifying power at this connector is a key step to rule out a wiring fault before condemning the solenoid.

Real Owner Repair Stories

• Ford F150 Forum user report (2017 Ford F-150 3.5L EcoBoost (same VCT system principles)) — Check Engine Light with codes P0021 and P0025 immediately after a cam phaser replacement job.
  ❌ Tried (didn't work) Swapping the new VCT solenoids with the original ones.
  ✅ What actually fixed it The electrical connectors for two of the VCT solenoids had been accidentally swapped during reassembly. Reversing the connectors to their correct positions resolved the codes.
• fordtransitusaforum.com user report (2020 Ford Transit 3.5L EcoBoost) — Check Engine Light with code P0025.
  ❌ Tried (didn't work) Oil and filter change.
  ✅ What actually fixed it The dealer diagnosed and replaced the Bank 2 (driver's side on that vehicle) exhaust VCT solenoid, which fixed the issue.

OEM Part Supersession History

• AT4Z-6M280-A → AT4Z-6M280-B or AT4Z-6M280-C — Manufacturer revision for improved durability or performance, possibly to better resist sticking from oil debris.
  Heads up: The newer revisions are the correct service replacements.