I was stuck in traffic (stop and go) for about 15 minutes and as I was pulling out of the traffic my car suddenly hesitated and check engine light came on. My civic LX has 140 000 Km and is well maintained, so I was surprised to see the light this early since this is my 5th honda and check engine light usually comes on around 250 000 Km and its usually the O2 sensor. This time my car hesitated everytime I revved around 3000 rpm so something else was up. Dealer diagnosed it as Code P6246 VTEC control arm actuator stuck in position 1. Turns out the car detected low oil pressure and therefore runs in back up mode (low revs) and the vtec won't engage. Dealer checked the oil, all switches and could not come up with anything. Just in case I did an oil change a little early. About a month later again I was stuck in traffic for about 30 mins and all of a sudden again the car hesitated and again check engine light comes on. Dealer saw same code and were baffled. I researched countless forums and very little info and most suggested changing oil pressure switch or vtec switch but no one ever wrote back to confirm. In my case dealer changed both the oil pressure switch and the vtec switch and honda canada paid for both parts and I just payed the $100 labour. Two months later no problems so the problem was on of those but cant confirm which one even though they checked out fine in the initial diagnosis.

I will repost if I have any more problems. I should add I only use honda oil and filters and I guess while I was idling there is lower oil pressure and somehow the switch detected that it was too low and shut off the vtec system. I drove for 1 week highway and city but just kept my revs low.