P2646 Honda Code - Rocker Arm Oil Pressure Switch Circuit Low Voltage

I had this code once before; the oil level was very low and the screen on the pressure switch was clogged. Changed the oil and cleaned the screen, problem solved.
The code popped up again several years later; oil level was fine, but I had just cleaned the engine with a hose. Water must have gotten in the circuit; next day when the engine was dry, the CHECK ENGINE light went out and it ran fine. (Honda Element 2006)

Thank you for the information!! Very helpful

I have a 2003 accord it gave me code p2646 I replace the vtec oil pressure switch I bougth it at the dealer and it still come up with the same code my car drives ok until i hit the gas pedal hard it starts studduling wen i let the gas go and press the gas soft it drives ok until i hit the gas again hard don't know wath else to do

Usually replacing the sensor fixes the problem. Are you using the engine oil weight recommend by the factory? is the oil level OK?

I have been diagnosing a friend's 2000 Honda accord EX 2.3L V-Tec. The car threw only one code P0420 (system catalyst below threshold). Car was severely bogging/lacking power & it seemed to get worse at higher RPMs.
I quickly ruled out a clogged catalytic convertor & looked at the operational data via a decent scanner. Started testing wires & sensors according to where the data led.
Removed the intake manifold to clean out the oil buildup from a non-functioning PCV system.
Knowing absolutely nothing about V-Tec systems I didn't even consider it.
While paging through the repair manual I bought I came across it (pg. 2A-4 of the Haynes) & the list of sensors used in V-Tec operation caught my eye because it's the exact list of info in my scanner's freeze frame data related to the engine code. All the operational data I retrieved started to make sense. After learning more about how the V-Tec worked I started testing the associated wiring & sensors. Already had a new intake temp sensor ready to go in (209*F seemed excessively high (is this normal? I almost never have to work on Honda engines so I wasn't 100%)).
Anyway, the purpose of this long winded story is that I found a shorted wire to the V-Tec oil pressure switch & wanted to remind everyone to check their wiring before wasting $ throwing new parts at it.
At 189k, even though I'm sure this is the only problem left, I think I'll remove, clean, & inspect the rest of the V-Tec assembly as well as adjust the valve lash.
Brilliant design! Simple, logical, & easy to work on! I have a new respect for Hondas!
Still reassembling but I have a question for the V-Tec veterans here... This seems like a no-brainer but I wanted other opinions..
I've seen comments/ problems regarding the system not activating & being intermittent...
What about activating at the wrong times? I'm wondering if false sensor information (shorted V-Tec oil pressure switch wiring & intake temperature sensor reading too hot) can trick the ECM into misadjusting the variable timing? V-tech only has 3 different valve time adjustments right?

Do you happen to have a visual guide that could help me with checking and repairing the wiring?

I had the same problem . What sensor are you saying fixes the problem? I replaced the VTEC valve, oil pressure switch, etc..... Thank you !

What model and year is your Honda? what oil weight are you using?

2004 Honda Element . I don't know off the top of my head. I've been going to the dealership to get my oil changed.

So how do I know of the right oil is in my car? I have had my oil changed twice since the problem started at two different locations.

Usually replacing the Rocker Arm Oil Pressure Switch takes care of the problem. There is even a factory service bulletin for that problem.

And if it doesn't is there anything else you could suggest ? I have replaced the part twice already and the car still has the same problems .

You have to use 5W-20 or 0W-20 Synthetic

And if the oil is correct and the part has been replaced and the wire is connected fine is there anything else it could be ?

The wire may be securely connected to the sensor, but the wire from the Engine Control Module (ECM) to the sensor may be broken. If the wire is not broken, then the problem is the ECM.

I have a 2003 Honda Accord ex and don't know what the problem is my car won't start

Does the engine cranks? have you check for fuel pressure?

Would faulty pressure switch or open circuit cause engine to act like it has rev limiter upon acceleration?.. 04 Honda Element.

Yes, you may experience a lack of acceleration if there is a problem with the VTEC system.

Ensure the screen located behind the VTEC oil pressure switch is removed and cleaned. If it is clogged up, you will just keep repeating the P2646 error code even if the switch is replaced.

Have an 07 Honda Civic ,code came up to be a vvt is this a fix emediatly or asap

Clean the oil tank with a bottle of cleaner they sell at autozone. Follow the instructions on how to clean it ( very easy) then change your oil and oil filter immediately. The whole process is easy and cheap. That will work miracles on your car. I had the same problem and code. I never replaced the sensor and my car now runs absolutely perfect

Great information. Thanks!!

I have a Honda Civic 2004, it gave me code 2646, I replace the Oring and VTEC gasket, but the problem continued

How is the engine oil level and condition? If the oil is OK, then you may have to replace VTEC oil pressure switch, as recommend by the factory service bulletin. See "Tech Notes" above.

2003 honda accord lx have code p2646 i change the solenoid spool value sensor it new from the dealer and the code keep coming up

I have the same problem on my accord

How is the engine oil level and condition? what oil weight are you using?

5w 20

Next step is to check the VTEC solenoid screen. See video above for information on how to do it.

Just wondering why the synthetic would be 0W20 instead of 5W20...? I've never heard of using a different viscosity when using synthetic. Is this a generic thing for all makes/models? My engine specs 5W20; would using 5W20 synthetic cause problems?

Most newer models use 5W-20 or 0W-20 Synthetic oil. All depends where you live.
You should have no problems using 5W20

Thank you. I appreciate your quick reply.
Mark :)

after replacing and cleaning screens and checking electrcal mechanic recomends running engine after adding some kerosine then changing oil. what do you all think?

computer or sludge in motor

Did you get this figured out. Im having same issue

ever figure out your issue. Im having same problem.

Yes, I had a very small oil leak that would show up when ever I accelerated. It took me almost three weeks to find but a few minutes to fix.

Just wondering did you get the check engine light off I am having the same issue

I have a Honda accord with this code p2646 car will not go over 3k revs. The wiring is fine and there is plenty of oil at the correct grade. Please help?

The P2646 code of for the VTEC oil pressure switch, but I haven't seen the switch causing that problem (not going over 3K revs). At this point you should start by changing the switch and clear the codes.

I changed the switch still have the same problem starting to wonder if the filters are clogged. Is it a good idea to flush the engine as it has done 160000 miles. Will this unclog the filters without dismantling the car.

Yes, flushing the engine could change. What model and year is your Honda? and what oil weight are you using?

2004 model I'm using oil weight 0-30 as that is what the car manufacture guides.

Ive completed all your steps and when i clear the code it works fine for about a mile. Then the check ebdibe light cuts back on and the car cuts out at 3000rpms again. If i clear the code again runs fine then does the same thing what can i try.

So I have this code on my 07 pilot ex 2wd...I've seen there are two oil pressure related items on these pilots...a pressure switch and a pressure sensor...which do I replace as one is $14 and the other is $130...

The oil pressure switch. Are you using the factory recommend oil weight?

Yes I'm using 5w20 and Honda oil filters...it's had the pcm replaced and the vtec actuator replaced...if the actuator is removed and put back on it will function for a few miles then go back to stuck off condition...

I'm

did you ever fix the problem on your car with code p2646

did you ever fix the problem with your car

Do this, and you should be ok. Problem is the filter going really dirty.
https://youtu.be/PknGSpDsmiI

So how did you fix it (small oil leak)? I have already changed the whole rocker arm assembly and clean the screen.

Still getting the same check engine light from time to time. I have the same year Honda as yours.

Jason, did you find a solution? I also have a 2004 - still getting check engine light from time to time. I did clean the VTC strainer. It was hard to get to.

same symptoms here...followed all the steps as well.

Quincy

I have tge vsa light come on 2006 honda ossyes.what do i need to do to fix it

Have you checked for codes? what codes did you get? The P2646 is not related to the VSA light.

Will a P2646 code cause an inspection failure in New York State does anyone know?

I had a P1009 code on my 2007 accord 4cyl. So I replaced and cleaned the vtc strainer filter, cleaned and tested the vtc solenoid, and replaced the vtec solenoid filter. After test drive, there are two code: P1009 and P2649.
P1009: Variable Valve Timing Control (VTC) Advance Malfunction.
P2649: Rocker Arm Oil Control Solenoid Circuit High Voltage.
Anyone know what cause the problem? Thanks....

According to a national database of repairs for your model year, the most likely cause of the problem is the Variable Valve Timing Control solenoid. Also, make sure you are using the correct engine oil weight.

I'm so impressed with the amount of instructions so received having checked the details of the auto code P2646 ROCKER ARM OIL SWITCH a circuit low voltage malfunction. Meanwhile, replacement had been made of this switch, still my car HONDA ACCORD 2004 still find it difficult to stop jerking as it accelerates to about 40km/hr. As you apply more pressure the jerking persists. Can there be any further assistance please, for the car to function perfectly like in the past.

Do you have 4 or 6 cylinder engine?

I have 4 cylinder engine.

What engine oil weight are you using? There is factory service bulletin for the P2646 code, but the bulletin just recommend changing the Rocker Arm Oil Switch. If the engine oil is OK and you have a new switch, the next step is to replace the Variable Valve Timing Control solenoid.

Would this problem cause a loud rattle from the rocker arms? 2004 civic si pulling a p2646. It had a light rattle around 3000rpm (highway rpms lol) but CEL came on and rattle got very loud one afternoon. I didnt drive after, pulled over and tow. Could this solenoid failure cause the noise? Or is there more to it.

How is the engine oil level and condition? from what you described, sounds like the engine's oil level is low.

The oil level was fine, oil changed the week before new filter as well. When I pulled over and checked there was still the proper amount of oil, and the proper weight.

When the car was purchased a week ago, the oil was a bit low and quite dirty. If that helps.

The lack of oil change probably cause the valve to stick, which will trigger the P2646 code, but I believe the loud rattle noise is more than that. Usually the complaint is just for engine light, but not for rattle.

Alright, thanks for the advice. I suppose the old saying hope for the best and expect the worst certainly applies. It's a shame, I love that car and have absolutely babied it in the short time I've owned it. Hoping the previous owner felt the same and that this bark is actually worse than the bite I am expecting.

When you say cleaner, do you mean something like seafoam? Pr is this a different cleaner? Please provide name of the cleaner so I can purchase it.

Hello there! I'm trying to find where I can buy the oil pressure switch and the o-ring so that I can fix my car. It's an '05 Element and I can't seem to find the parts I'm looking for. Please help; this is my daily driver and I can't afford to be without it!

Have you tried the dealer or AutoZone?

Rock Auto has the whole VTEC assembly for $70. The dealer wants $170

Hi,
I have a 2008 Odyssey iVtec 2.4, I am having the P2646 VTEC Pressure Switch Circuit Voltage Low code.
Do I change the oil pressure switch too? I am having problem to locate it....Please help

What model do you have EX, EX-L, LX or Touring? Also, according to factory service manual, there should be a 3.5L engine in your Odyssey

I have a 06' Honda Odyssey with a 3.5L. It will not go above 3000RPM. I changed the oil and Changed the VTech assembly. I'm still having the same problem. I can't find a single wiring diagram that shows my type of VTech. Every VTech diagram I find is for a single wire to the solenoid. Mine has three wires to the PSI switch and two wires to the solenoid.

2005 Civic EX 1.7l VTEC, I replaced the Variable Valve Timing Control solenoid, ran oil cleaner and changed the oil with factory-recommended weight and filter. Still getting P2646, and sometimes getting P0420, can't accelerate above 4,000rpm. Next step?

Your next step is to check or replace the VTEC Pressure Switch (or Rocker Arm Oil Pressure Switch).
The P0420 code is probably no related to the P2646 code. For the P0420 you should start by using high octane gas. If the problem persists after a couple of weeks, then you may have to replace the catalytic converter.

It's one unit, from O'Reillys for about $150, the pressure switch is attached when I bought it. I checked the connections and used a little dielectric grease to ensure good connections.
https://www.oreillyauto.com...

hi everyone i have a lil problem. i changed the Solenoid on my car. my Car is a 2009 Honda Crv code p2646. i always got a oil change. my Check Engine light and VSA light are still on. what else can i do . pls help me. pls email me. [email protected]

Which Solenoid did you replaced? one of the most common problem is the Rocker Arm Oil Pressure Switch

My 2003 Element earned over 250k miles on it. Regular oil changes. Ran like a dream. I never experienced this issue. But then after a hit-and-run ruined my motor (long story), I had to swap it out with a JDM engine. I got one with 45k miles on it. Worked great for a while but now I get code p2646 on occasion. Found I had an oil leak so the level would get low and throw this error. When I topped off the oil, the error went away. Easy fix! I haven't gotten this error in some time by keeping the oil topped off.

But now I JUST had the oil changed last week and I am getting this error again. I will check that the techs changed out with the proper weight oil and that the level is still good but could topping the oil levels cause a "need-to-be-replaced" sensor to stop sending the p2646 error? I am trying to isolate my actual issue here.

Also I have heard people swear by Marvel's Mystery Oil and use Seafoam for cleaning out the oil passages and screens. Anyone have any feedback on that?

Thanks!

Also I have heard people swear by Marvel's Mystery Oil and use Seafoam for cleaning out the oil passages and screens. Anyone have any feedback on that?

Yes that will definitely help, not only the VTEC Solenoid Valve, but also other parts of the engine.

You should also try removing the Rocker Arm Pressure Switch and check if there any debris or anything else causing the bad reading.

I replaced the Vtec valve and oil pressure switch as one unit. But I still keep getting the P2646 code. Oil level is correct. Just changed it with the correct weight.

Let me check if I can find more information. What model and year is your Honda?