p2646 code after head gasket replacement, need help.

j450nb

New Member
im struggling with this stupid VTEC sensor on the passenger side of the head it keeps throwing the p2646 code (A Rocker Arm Actuator System Performance Stuck Off Bank 1). I changed the oil, replaced the oil pressure sender switch on the Vtec actuator, and after those didnt fix it i replaced the entire Vtec actuator with a new honda part for $200. Its still throwing the code.

This issue started a few months ago when a local shop replaced the Head gasket. Code popped up the day after i took the car home from the head gasket job. They decked the head and replaced the gasket which solved the overheating issue i chased for months.

Given the head gasket job they did, is there a chance something is bad inside the head from the shops handy work or does this sound like an electrical issue (pinched wire etc)? I took it back to the shop that did the head gasket job and they trouble-shot until they got to the point where they had to confirm the vtec actuator's sensor was getting oil pressure which they dont have the special service tool for and are now telling me to go to honda for diagnostic. Now honda is going to rail me for a few hours of labor to diagnose something i am fairly certain is related to this head gasket job. Do you guys have any input about potential causes here for this code? I have replaced the entire part that i am seeing is even related to this code.

2005 Civic EX 140K miles. COMPLETELY STOCK, hasnt been abused its my daily driver just FYI.
 

dancam

Member
Registered VIP
Lame. Well, keep in mind that what i am saying is guesswork, but if you have the inclination you can troubleshoot some more yourself. Find a haynes manuel and see what the voltage to the actuator is supposed to be. Generally its either 5 volts or 12, usually 12. Supply that voltage the old one you took out and see if it moves or does what its supposed to. If not it was that part and do the same test on your new installed one. If it does move or work then your pressure sensor or wiring is suspect. If the new one in your car also checks out and If your eager to fix it yourself go to a wrecker and get a pigtail that plugs into this actuater. Wire it up so you can manually switch the vtec on and off. Have it off, floor it while speeding up and switch it on around 4500-5000rpm. You will be able to feel it if it is working. I had my 2005 coup vtec on a manuel switch. Oh, that means it is 12 volts, as thats what i had it hooked up to. If you feel it working that means its your pressure switch or the wiring to the actuater. If you cant feel it then what most likely happened is the shop removed your rocker assembly to machine the head and put something back together wrong. Or they left it in and bent something by accident or got some metal shavings in there while machining the head so that the actuator cant move anything even if its trying.
If its the pressure sensor or wiring then splice another wire into where the signal comes out of the pressure switch. Brig that into your car and hook it up to a voltmeter, go for a drive and rev it up, floor it a bunch to get the vetec to kick in and see if it sends a signal. If yes then its the wiring and if no then its a faulty switch again.
Do all vehicle on tests with the engine warm to activate te vtec. You made sure all the electrical connections were tight right? Took your grounds off and cleaned them? The code for sure got cleared after you replaced the part?


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