OK have had a CEL for a month or so and when the MPG's dropped to about 24, after being around 30, I decided it was time to see what was what. I checked the CEL's and got codes 1 (Oxygen Sensor 1), 10 (Intake Air Temp Sensor), 22 (VTEC Pressure Valve), and 23 (Knock Sensor). Then reset the ECU by pulling the Backup and ECU fuses from under the hood for a few minutes. When I turned the car on a CEL popped right up, I took the car for a quick drive around the block, turned it off and rechecked the CEL. I only came up with code 22 (VTEC Pressure Valve). I would venture a guess that I should replace the VTEC Solenoid and Gaskets.

My question here is would a faulty VTEC Solenoid cause low MPG's?

 

You suppose the other codes would pop if VTEC were staying on all the time?

I.e. O2 and knock because it's lean, IAT because all four valves are open?

Totally guessing on my part.

OTOH, is there a common ground for all of those things that could be loose and affecting them all?