Been going crazy with VTEC system codes on 2.4 engines
2003 CR-V with 199K miles
Been showing P1259 code right after I bought it. Will usually go on in the first few miles of driving and they may come on at random times. Limits RPM to 2800. If I turn off ignition and start right back up it clears rev limiter and can drive normally for a while.
Have done all of the following fixes one at a time with no difference each time.
Changed oil & filter 5W-20
Changed VTEC solenoid filter and gasket, filter & gasket at front of block and cleaned screens on long valve at end of block.
Replaced VTEC oil pressure switch
Replaced entire VTEC solenoid assy including another oil pressure switch. Old assy looked almost new and was probably replaced by previous owner
Added motor flush to oil - let idle for 5 min as recommended. Drained and changed oil twice to make sure all flush was out.
Changed oil pressure sending unit below VTEC solenoid
Not sure where to go from here - oil and screens and spotlessly clean. Pulled valve cover and found no sludge buildup - everything clean

Yesterday my 2005 Element with 212K miles decided to show P2646 code. Appears to be a similar issue with VTEC solenoid. However on this one the rev limiter comes right back on within a minute after I turn engine off and on so this vehicle is undriveable now. Swapped out the VTEC assy with the first one that I took off the CRV with no effect.
Any suggestion as where to go next would be helpful. Have tried all the "fixes" that I could find online.

 

Looking at the factory service manual. Not seeing a P1259.

The P2646 is VTEC Oil Pressure Switch Circuit Low Voltage. FSM lists low on oil, bad pressure sensor, faulty wiring, PCM update, faulty PCM.