Oct 192017
 

Honda Odessy

I have a 2006 Honda Odyssey EX-L. i-vtec VCM. It started running badly, very rough, would die in gear at idle. Had code P2647 VCM system stuck ON. I removed and clean the VTEC Spool Valve, EOP Switch and VTEC Solenoid. Reinstalled and cleared the code. The code did not come back but now I get misfires on all cylinders. I checked the timing belt to see if it slipped but it hadn’t. I replaced the timing belt while I was that far. Back together but still get pretty equal misfires on all cylinders.
I performed a leak down test on all cylinders. Cylinders 4, 5 &6 are all less than 10%. Cylinders 1, 2 &3 are at 80% loss on all cylinders. This is the head designed to shut down cylinders. There’s air through the exhaust and also air coming from the valve cover PCV connections.


It has been my experience in the past, that when our shop replaced just the switch it never repaired the vehicle but when we replaced the whole vtec assembly it would. This is especially true when there is any amount of sludge in the motor which is common on these engines.

I’m still a believer though that the valve assemblies themselves are sludging up causing the pressure switch to read incorrectly. Everyone that I’ve replaced has been sludged in the valve and the screen filter in the gasket.

Honda Code P2647 – Rocker Arm Oil Pressure Switch Circuit High Voltage

Code P2647 Possible causes
  • Check engine oil level, oil condition and pressure
  • Faulty Variable Valve Timing and Lift Electronic Control (VTEC) / Rocker Arm Oil Pressure Switch
  • VTEC/Rocker Arm Oil Pressure Switch harness is open or shorted
  • VTEC/Rocker Arm Oil Pressure Switch circuit poor electrical connection

 

Code P2647 Description

The VTEC system activates the rocker arm oil control solenoid (VTEC solenoid valve) by command from the engine control module (ECM)/powertrain control module (PCM), and it charges/discharges the hydraulic circuit of the VTEC mechanism that switches valve timing between Low and High. The ECM/PCM monitors oil pressure in the hydraulic circuit of the VTEC mechanism using the rocker arm oil pressure switch (VTEC oil pressure switch) downstream of the rocker arm oil control solenoid (VTEC solenoid valve). If there is a difference between the oil pressure condition in the hydraulic circuit that is determined by the ECM/PCM command and the oil pressure condition that is determined by the status of the rocker arm oil pressure switch (VTEC oil pressure switch), the system is considered faulty, and a DTC is stored.

Source: Team Leader Tech

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