Understanding the Honda P2647 Code and VTEC System

How to Fix the Honda P2647 Code: A Comprehensive Guide

The Honda P2647 code is a common trouble code, especially in models like the Accord, Civic, CR-V, and Element. This code indicates a problem with the “A” Rocker Arm Actuator System Stuck On or a malfunction in the Variable Valve Timing and Lift Electronic Control (VTEC) system. When this code appears, it typically triggers the check engine light and may cause your engine to enter a “limp mode,” where it restricts performance to prevent damage.

In this guide, we’ll explore what the P2647 code means, its potential causes, symptoms, and how to fix the issue.

What Does the P2647 Code Mean?

The Honda P2647 code relates to the VTEC system, which adjusts the valve timing and lift to optimize engine performance under various conditions. The code indicates that the Engine Control Module (ECM) has detected that the rocker arm actuator is stuck in the “on” position, meaning it isn’t switching between the high and low camshaft profiles as it should.

Common Causes of the Honda P2647 Code

Low or Dirty Engine Oil: VTEC systems rely heavily on proper oil pressure and clean oil to function correctly. Low oil levels, dirty oil, or a clogged oil filter can prevent the system from working properly.

Faulty Rocker Arm Oil Pressure Switch: This switch monitors oil pressure in the VTEC system and signals the ECM to activate or deactivate the system. If the switch is faulty, it can send incorrect signals, leading to the P2647 code.

Clogged VTEC Solenoid: The VTEC solenoid controls the flow of oil to the rocker arms. If it becomes clogged with sludge or debris, the VTEC system cannot operate correctly.

Wiring Issues: Damaged or frayed wiring connected to the VTEC solenoid or oil pressure switch can cause electrical issues that trigger the P2647 code.

This service bulletin #13-021 details a fix for a Honda P2647 code

Honda has issued a service bulletin 13-021 to address several trouble codes related to the VTEC system on the vehicles listed below. The trouble codes are:

• P2646/P2651 (rocker arm oil pressure switch circuit low voltage).
• P2647/P2652 (rocker arm oil pressure switch circuit high voltage).

Honda has determined that the rocker arm oil pressure switch may fail intermittently

Vehicles affected by Honda 13-021 service bulletin

2003–12 Accord L4
2012–13 Civic ALL except Si and Hybrid ALL
2002–05 Civic Si
2002–09 CR-V
2011 CR-Z
2003–11 Element
2007–11 Fit

How the Honda VTEC system works

The Honda variable cylinder management (VCM) system activates the rocker arm oil control solenoid (VTEC solenoid valve) when commanded by the powertrain control module (PCM). When operated, it either charges or discharges the hydraulic circuit of the cylinder pause VTEC system. The PCM monitors oil pressure in the hydraulic circuit of the VTEC mechanism using the engine oil pressure (EOP) sensor downstream of the rocker arm oil control solenoid (VTEC solenoid valve). If the PCM sees a difference between the oil pressure condition in the hydraulic circuit the system is considered faulty, and a DTC is stored.

Diagnose and fix Honda P2647 code, along with a P2646, P2651, and P2652

The Variable Timing/Lift Control (VTEC) oil pressure switch is located on the back of the cylinder block near the oil filter.

The VTEC oil pressure switch has a Blue/Black (BLU/BLK) wire. The switch is normally closed, so it grounds the reference voltage from the PCM when the key is in the RUN position. The PCM monitors the voltage drop to confirm that the switch is closed and grounded.

When the engine RPMs reach about 2,700 while driving, the PCM energizes the VTEC solenoid that allows oil pressure to flow into the intake valve rocker arms. The VTEC oil pressure switch senses the change in oil pressure and opens. The ECM sees the voltage rise, confirming that the switch is no longer grounded.

The trouble code will set if the VTEC oil pressure switch is not grounded when engine RPMs are below 2,700 and will also set a code if the oil pressure switch does not open at RPMs above 3,000.

If the code sets at 2700 RPMs or higher, start by

37250-PNE-G01 oil pressure switch

checking engine oil level. If it’s low, top off the oil, clear the code, and take the vehicle for a test drive. If the code reappears, replace the oil pressure switch with Honda switch 37250-PNE-G01 and O-ring 91319-PAA-A01

©, 2021 Rick Muscoplat