P2652 on 2017 Acura RDX: Rocker Arm Oil Pressure Switch 'B' (Bank 1) Stuck On Causes and Fixes

What's Unique About the 2017-2017 Acura RDX

On the 2017 RDX with the 3.5L V6 engine, this code is closely tied to the Variable Cylinder Management (VCM) system. The 'B' pressure switch monitors the oil pressure that actuates the VCM system on the rear bank (Bank 1). These switches have a very high failure rate on RDX, MDX, and other Honda/Acura models with the J35 engine. The issue is significant enough that Acura issued a Technical Service Bulletin (BTI&01192022901) to investigate vehicles that store P2652, often along with code P3400. 🎬 Watch: How to replace the oil pressure switch for code P3400 The location of the switch on Bank 1 (rear, near the firewall) can make access tight, often requiring a deep socket and a swivel joint for replacement.

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, sometimes flashing.
• Message on the dash like "Check Emission System".
• Vehicle enters 'limp mode,' limiting speed and acceleration.
• Rough engine idle or running conditions.
• Engine shuddering, juddering, or bucking.
• Engine revs up and down on its own while in Park.
• Strong smell of gasoline from the exhaust.

Most Likely Causes

1. Failed Rocker Arm Oil Pressure Switch 'B' (Bank 1) 🔴 High Probability → Shop Engine Rocker Arm This specific pressure switch (Part No. 37240-R70-A04) is a known high-failure part on Honda and Acura V6 engines. Technicians report replacing them frequently, sometimes multiple times a month.
   How to confirm: After confirming correct oil level and condition, the most practical test is to replace the switch. A more advanced test involves checking for continuity across the switch's terminal and its body (ground) with the engine off; if continuity exists, the switch is internally shorted and faulty. The switch is located on the rear cylinder head (Bank 1).
   Typical fix: Replace the Rocker Arm Oil Pressure Switch 'B' for Bank 1. The OEM part number is 37240-R70-A04. It is also recommended to replace the O-ring, part number 91319-PAA-A01. A 24mm deep socket is typically required for removal. 🎬 Watch: A step-by-step walkthrough of the switch replacement process
   Est. part cost: $45-$65
2. Low or Dirty Engine Oil 🟡 Medium Probability The VTEC and VCM systems use oil pressure to actuate mechanical components and are highly sensitive to oil level, viscosity, and cleanliness. Low or sludgy oil can cause the pressure switch to malfunction or the spool valve passages to become restricted.
   How to confirm: Check the engine oil dipstick to ensure the level is between the 'min' and 'max' marks. Check the oil's color and consistency. If the oil life monitor is low (e.g., 5%), it can be a contributing factor.
   Typical fix: Perform an oil and filter change using the correct full synthetic 0W-20 oil. Clear codes and see if the issue returns.
   Est. part cost: $40-$80
3. Incorrect Aftermarket Oil Filter ⚪ Low Probability Some forum users report that certain aftermarket oil filters without the proper internal bypass valve pressure specifications can cause oil pressure deviations on Honda/Acura V6 engines, potentially triggering this code.
   How to confirm: Check the brand and part number of the installed oil filter. If it is not a known quality brand or an OEM filter, consider it suspect.
   Typical fix: Replace the oil filter with a high-quality aftermarket brand (like WIX, Denso) or an OEM Honda/Acura filter (Part No. 15400-PLM-A02).
   Est. part cost: $10-$20

Rare But Worth Checking

• Wiring or Connector Issue: The wiring harness or connector for the switch could be damaged, corroded, or have a poor connection, causing a high voltage or 'stuck on' signal. This is worth checking before replacing parts, especially for rodent damage.
• Clogged Oil Passages or Faulty Spool Valve Assembly: Sludge or debris can clog the small oil passages or filter screens within the rocker arm oil control valve (spool valve) assembly where the switch is mounted. In rare cases, the entire spool valve assembly (Bank 1 VCM Oil Control Valve, Part No. 15810-R70-A04) may need to be cleaned or replaced, which is a much more involved and costly repair.

Diagnosis Steps

1. Verify the engine oil level and condition. If low or dirty, perform an oil and filter change with full synthetic 0W-20 oil. Clear codes and test drive.
2. If the code returns, locate the Rocker Arm Oil Pressure Switch 'B' on Bank 1. This is the rear cylinder bank, closer to the firewall. The 'B' switch is part of the VCM spool valve assembly and is often the one with a brown connector, closer to the intake manifold.
3. Inspect the electrical connector and wiring for any signs of damage, corrosion, or loose connections. Pay close attention to signs of rodent activity.
4. Using a 24mm deep socket, replace the switch (Part No. 37240-R70-A04) and its O-ring (91319-PAA-A01). Access may be tight.
5. Clear the codes and perform a test drive. This resolves the issue in the vast majority of cases.
6. If the code persists, a more advanced diagnosis is needed. This involves testing for a short in the wiring to the PCM or testing the oil pressure at the switch port with a mechanical gauge to check for a blockage in the spool valve assembly.

Parts You'll Likely Need

• Rocker Arm Oil Pressure Switch Assembly (OEM #37240-R70-A04) — This is the component that directly reports the VCM pressure reading to the ECM. It has a very high failure rate on this platform and is the most frequent cause of code P2652.
  Trusted brands: Acura/Honda (Genuine OEM), Standard Motor Products (PS533), NTK (NGK)
  OEM price range: $45-$65
  Aftermarket price range: $15-$40
• Oil Pressure Switch O-Ring (OEM #91319-PAA-A01) — It is best practice to replace the O-ring when replacing the switch to prevent oil leaks. It is often sold separately.
  Trusted brands: Acura/Honda (Genuine OEM)
  OEM price range: $2-$5
  Aftermarket price range: $1-$3

Related Codes That Often Appear With This One

• P3400 — P3400 indicates 'Valve Pause System (VPS) Stuck Off Bank 1'. Since the P2652 switch directly monitors this system's oil pressure, a faulty switch reading ('stuck on') logically triggers a corresponding system performance code. Acura's TSB BTI&01192022901 specifically links these two codes as a known pairing under investigation.

Technical Service Bulletins (TSBs) & Recalls

• BTI&01192022901: A request from Acura to investigate 2017 RDX, MDX, RLX, and TLX vehicles with a client complaint of the Malfunction Indicator Light (MIL) on with DTC P2652 and/or P3400 stored. This was an information-gathering bulletin, not a repair procedure.

Platform-Specific Known Issues

• Acura issued a Technical Service Bulletin (BTI&01192022901) requesting dealerships to collect information on 2017 RDX models that have both P2652 and P3400 codes stored, indicating a known issue the manufacturer was actively investigating as of January 2022.

Mechanic-Grade Diagnostic Values

• Rocker Arm Oil Pressure Switch 'B' Continuity — expected: No continuity (Open circuit / O.L.) between the switch's electrical terminal and its metal body (ground) when the engine is off.. Failure: Continuity (a low resistance reading, near 0 ohms) exists with the engine off. This indicates the switch is internally shorted and 'stuck on'.
• Scan Tool Live Data: Rocker Arm Oil Press SW (Bank 1) — expected: The status should read 'OFF' when the ignition is on but the engine is not running.. Failure: The status reads 'ON' with the ignition on and engine off. This electronically confirms the switch is stuck in the closed position or the signal wire is shorted to ground.
• VCM System Oil Pressure (at switch port) — expected: Pressure should be below 45 kPa (6.5 psi) when the VCM system is commanded off.. Failure: Pressure remains above 45 kPa (6.5 psi) even when VCM is off, indicating a mechanical or hydraulic issue in the spool valve, not a faulty switch.

Scan Tool Commands That Help

• Honda Diagnostic System (HDS) or equivalent professional scanner: VTEC+VCM TEST (specifically the CDVEB TEST) — This bidirectional test is used to command the VCM system on and off. It allows a technician to verify if the spool valve solenoid is working and to observe the oil pressure switch status change in live data. If the system is commanded OFF but the switch status remains ON, it strongly confirms a faulty switch or a wiring short to ground.

Wiring & Ground Locations

• PCM Connector C, Pin 34 — On the Powertrain Control Module (PCM), which is typically located in the engine bay or behind the dashboard/center console.. This is the specific pin where the signal wire (typically Green) from the Rocker Arm Oil Pressure Switch 'B' (Bank 1) terminates. A technician can test for a short to ground on this wire by checking for continuity between this pin and the chassis ground with the PCM and switch disconnected.
• G101 — A primary engine/transmission ground point, typically a bolt on the transmission housing or engine block near the front of the engine bay.. While a fault at G101 would likely cause multiple codes, a poor engine ground can lead to erratic sensor readings. The oil pressure switch grounds through its body to the engine block, making this main ground connection critical for a stable electrical system.

Real Owner Repair Stories

• AcuraZine Forum User (2017 Acura RDX Tech) — Sudden limp mode, flashing check engine light, juddering/shuddering, vehicle would not accelerate properly.
  ❌ Tried (didn't work) The owner suspected a transmission failure due to the severe symptoms.
  ✅ What actually fixed it The dealership diagnosed code P2652 and replaced the faulty rocker arm oil pressure switch on Bank 1, which resolved all symptoms.
• OdyClub (Honda Odyssey) Forum (2016 Honda Odyssey (same 3.5L V6 family)) — Flashing check engine light, limp mode.
  ✅ What actually fixed it Owner replaced the Bank 1 (rear) VCM oil pressure switch, Part No. 37240-R70-A04. This fixed the issue completely.

OEM Part Supersession History

• 37240-R70-A02, 37240-R70-A03 → 37240-R70-A04 — Part revision by the manufacturer, likely to improve reliability and address the high failure rate of the earlier versions.
  Heads up: While older versions will physically fit, it is highly recommended to use the latest part number (37240-R70-A04) to benefit from the design improvements.