P3400 on 2017 Honda Ridgeline: Valve Pause System (VPS) Causes and Fixes

What's Unique About the 2017-2017 Honda RIDGELINE

The 2017 Ridgeline uses the J35Y6 3.5L V6 engine, which features Honda's Variable Cylinder Management (VCM) system. This system is entirely dependent on clean engine oil at the correct pressure to hydraulically actuate the rocker arms and deactivate cylinders. Consequently, these engines are highly sensitive to oil level, condition, and the health of the oil pressure switches that monitor the system. A failure in one of these simple switches is a very common reason for VCM-related codes like P3400 across many Honda and Acura V6 models. Some owners choose to install an aftermarket VCM disabling device to prevent these issues altogether.

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 (Malfunction Indicator Light) is on
• Rough engine running or idling, sometimes described as 'chugging'
• Decreased fuel economy
• ECO mode light will not turn on
• Engine shuttering or hesitation under acceleration

Most Likely Causes

1. Faulty Bank 1 Rocker Arm Oil Pressure Switch 🔴 High Probability This is a very common failure point on Honda V6 engines with VCM. The switch can fail intermittently or become clogged with sludge, sending incorrect data to the ECU. Honda has issued communications to dealers to investigate this specific issue on 2017 Ridgelines.
   How to confirm: The switch for P3400 (Bank 1) is located on the rear cylinder head, 🎬 Watch: How to locate the different oil pressure sensors. near the firewall. A clever diagnostic trick is to swap the identical front (Bank 2) and rear (Bank 1) switches. If the code changes to P3497 (Bank 2), the switch is confirmed faulty. The switch can also be tested for continuity with a multimeter; it should have continuity when the engine is off and no continuity when running.
   Typical fix: Replace the Bank 1 (rear) rocker arm oil pressure switch and its O-ring. This requires a 24mm deep socket. 🎬 Watch: A step-by-step guide to replacing the oil pressure switch. The torque spec for the new switch is approximately 13-16 ft-lbs.
   Est. part cost: $30-$60
2. Low Engine Oil Level or Pressure 🔴 High Probability The VCM/VPS system is hydraulic and requires sufficient oil pressure to function. If the oil level is low, the oil pump cannot supply adequate pressure to the cylinder heads to deactivate the valves. Some VCM-equipped engines can consume oil between changes, making regular checks critical.
   How to confirm: Check the engine oil dipstick on a level surface. This should always be the first step in diagnosing this code. 🎬 See why checking your oil level is the best first step.
   Typical fix: Top off the engine oil to the correct level. If the oil is old or dirty, perform an oil and filter change. After topping off, the code may clear on its own after several drive cycles.
   Est. part cost: $0-$70
3. Dirty or Incorrect Viscosity Engine Oil 🟡 Medium Probability Old, sludgy, or incorrect weight oil can clog the small passages in the VCM system or the screen on the oil pressure switch itself, preventing proper operation. The system is designed for 0W-20 synthetic oil.
   How to confirm: Check the condition and maintenance history of the engine oil. If it's dark, thick, or past its change interval, it should be replaced.
   Typical fix: Perform an engine oil and filter change using the manufacturer-specified oil viscosity (0W-20).
   Est. part cost: $40-$80
4. Wiring or Connector Issue ⚪ Low Probability While less common, a loose connection, a corroded pin, or a damaged wire leading to the Bank 1 oil pressure switch can interrupt the signal to the ECU. The connector's location at the rear of the engine bay can make it susceptible to collecting debris.
   How to confirm: Visually inspect the electrical connector and wiring harness for the Bank 1 oil pressure switch for any signs of damage, corrosion, or looseness. Ensure the connector is fully seated.
   Typical fix: Repair the damaged wiring or clean the connector pins and secure the connection.
   Est. part cost: $5-$50

Rare But Worth Checking

• Faulty VCM Solenoid: The solenoid assembly (spool valve) controls oil flow to the rocker arms. While less common than a switch failure, a stuck or failed solenoid can cause this code. The screens on the solenoid gasket can also become clogged.
• Internal Engine Oil Pressure Issue: In rare cases on some Honda V6 models, a faulty oil pump relief valve spring can cause excessively high oil pressure on a cold start, triggering P3400 and P3497. This was addressed in TSB 13-055 for earlier model years but highlights the system's sensitivity to pressure regulation.

Diagnosis Steps

1. Check the engine oil level using the dipstick. If low, top it off with 0W-20 oil, clear the code, and drive to see if it returns. This is the most common fix.
2. Inspect the quality of the engine oil. If it is dirty, sludgy, or overdue for a change, perform an oil and filter change.
3. Scan for other DTCs. Note if P2652 is also present, as this strongly points to the Bank 1 oil pressure switch.
4. Locate the Bank 1 (rear) and Bank 2 (front) rocker arm oil pressure switches. They are identical parts.
5. As a definitive test, swap the front and rear oil pressure switches. Clear the codes and drive. If the code changes from P3400 to P3497, the switch you moved to the front is faulty.
6. Inspect the Bank 1 switch's electrical connector and wiring for damage or corrosion. Ensure it is securely clipped on.
7. If the switch is confirmed to be faulty, replace it using a 24mm deep socket. Always replace the O-ring (part #91319-PAA-A01) at the same time and lubricate it with fresh engine oil before installation. Torque the new switch to 13-16 ft-lbs.
8. Clear the diagnostic trouble codes and perform a test drive to ensure the code does not return. The light may also go off on its own after several drive cycles.

Parts You'll Likely Need

• Rocker Arm Oil Pressure Switch (Bank 1) (OEM #37240-R70-A04) — This switch is the most common point of failure for code P3400. It either fails electronically or gets clogged, providing an incorrect reading to the computer. This part number supersedes older versions like 37240-R70-A03 and 37240-R70-A02.
  Trusted brands: Honda (Genuine OEM), NGK, Standard Motor Products, URO Parts
  OEM price range: $45-$65
  Aftermarket price range: $25-$45
• Oil Pressure Switch O-Ring (OEM #91319-PAA-A01) — This O-ring should always be replaced with the pressure switch to prevent oil leaks. It is often sold separately.
  Trusted brands: Honda (Genuine OEM)
  OEM price range: $2-$5
  Aftermarket price range: $1-$3

Related Codes That Often Appear With This One

• P2652 — P2652 means 'Rocker Arm Oil Pressure Switch B (Bank 1) Stuck On'. This code and P3400 are frequently stored together as they relate to the same component. A TSB from Honda (ATI&01192022901) specifically links these two codes, indicating a fault with the Bank 1 oil pressure switch.
• P3497 — This code is 'Valve Pause System Stuck Off Bank 2'. If both P3400 and P3497 appear, it strongly suggests a global oil pressure problem, such as a very low oil level or a failing oil pump, affecting both cylinder banks.

Technical Service Bulletins (TSBs) & Recalls

• ATI&01192022901: A request for information from dealerships regarding vehicles with DTC P2652 and/or P3400 stored, to better understand

Platform-Specific Known Issues

• Honda issued Technical Service Bulletin (TSB) #ATI&01192022901 which is a request for information from dealerships regarding 2017 Ridgeline, Pilot, and Odyssey models that store both P3400 and P2652, often accompanied by a rough running condition. This indicates Honda is actively investigating the root cause on this platform.
• Owner Experience: Many owners on forums like Reddit and in YouTube repair videos confirm that the first and most important step is checking the oil. Several successful DIY repairs involved simply topping off the oil, clearing the code, and having it not return.
• Repair Experience: Accessing the rear (Bank 1) switch can be tight, but is achievable with a 24mm deep socket and a ratchet. It is not necessary to apply liquid gasket to the threads of the new switch, only to install the new, lubricated O-ring.

Mechanic-Grade Diagnostic Values

• Rocker Arm Oil Pressure Switch Continuity — expected: There should be continuity to ground with the engine stopped.. Failure: There should be NO continuity to ground with the engine running. If continuity exists while running, or no continuity exists while stopped, the switch is faulty.
• Rocker Arm Oil Pressure Switch Installation Torque — expected: 22 N.m (16 lb-ft). Failure: Over-tightening can damage the switch or threads; under-tightening can cause oil leaks.

Scan Tool Commands That Help

• Honda Diagnostic System (HDS): Snapshot Function / Data List Display — To capture and monitor the real-time status (On/Off) of the Bank 1 and Bank 2 rocker arm oil pressure switches during a test drive. This allows a technician to see if the switch signal is intermittent or fails to change when the VCM system is commanded to activate, which helps differentiate a wiring issue from a faulty switch.

Wiring & Ground Locations

• Engine Bay Ground Point Modification — An unused, pre-threaded M6x1.0 hole on the driver's side fender/chassis structure, near the fuse box and battery.. The 2017 Ridgeline lacks an easily accessible negative ground post for testing or jump-starting, requiring removal of the air intake. Technicians and owners can install a 40mm M6x1.0 bolt in this location to create a permanent, reliable ground point for any under-hood electrical diagnosis, including testing the P3400 circuit.
• Official Wiring Diagrams — Available via Honda's technical information website (techinfo.honda.com).. The official Electrical Wiring Diagram (EWD) is the definitive source for connector pinouts, wire colors, and ground locations (like G101) for the J35Y6 engine, which is essential for diagnosing a potential wiring fault between the oil pressure switch and the PCM.

Real Owner Repair Stories

• Reddit user on r/HondaOdyssey (2013 Honda Odyssey (similar J35 engine with VCM)) — P3400 code appeared.
  ❌ Tried (didn't work) Initially unsure of the cause.
  ✅ What actually fixed it The owner swapped the front (Bank 2) and rear (Bank 1) oil pressure switches. The code changed to P3497 (Bank 2) after a few weeks, confirming the original switch was faulty. Replacing the bad switch resolved the issue.
• YouTube channel 'Cranberry Place Farm' (2012 Honda Accord EX-L V6, 55,000 miles) — Check Engine Light with code P3400.
  ❌ Tried (didn't work) Initial diagnosis pointed directly to the sensor.
  ✅ What actually fixed it The owner replaced the rear (Bank 1) rocker arm oil pressure switch (part # 37240-R70-A04) and the corresponding O-ring. After clearing the code, the check engine light stayed off.
• YouTube channel 'Fix It All' (2015 Honda Pilot (similar J35 engine with VCM)) — Check Engine Light with code P3400, ECO light would not turn on.
  ❌ Tried (didn't work) Clearing the code without repair.
  ✅ What actually fixed it The owner replaced the Bank 1 (rear) oil pressure sensor. After the repair and clearing codes by disconnecting the battery, a test drive confirmed the ECO light began working again, indicating the VCM system was functional and the fix was successful.
• YouTube channel 'DIY Reid' (2010 Honda Odyssey, 136,000 miles) — P3400 code, intermittent at first then solid.
  ❌ Tried (didn't work) Driving to see if the light would clear on its own.
  ✅ What actually fixed it The immediate fix was discovering the engine was low on oil and topping it off. The light went out after about 800 miles. However, to address the root cause of the oil loss, the owner later replaced the PCV valve and the VTEC solenoid seal.

OEM Part Supersession History

• 37240-R70-A01, 37240-R70-A02, 37240-R70-A03 → 37240-R70-A04 — Standard part revision and improvement by the manufacturer.
  Heads up: None found. The latest part number (37240-R70-A04) is the correct and compatible replacement for all previous versions for this application. The same part is used for both Bank 1 and Bank 2.