[larrh7]

Update on code. Check engine light cleared for about a week. Came back on and stayed on. Took it to Advance Auto and they said it was a different code. I think it was 0325. He said knock sensor. Took it to my local mechanic and he got the same code. Put a new knock sensor in and it's running great and no check engine light. Not sure what happened to the other code but it's gone. Makes no sense to me. Hopefully she keeps running like it is.

 

[wingingEd]

I've read all these posts, and did everything suggested trying to solve the P2646 on my 2003 Element. I changed the oil, flushed and changed oil again, put in heavier oil, replaced the spool valve assembly(twice), the cam gear, the wire connectors, the ECM, checked oil pressure, etc.... , but still got the P2646 and bucking engine. Having said all that, today I made a discovery. Since my car only did this after a short warm up, I tried disconnecting the temperature sensor in the head and wow! no more P2646 or bucking. Of course that throws a temperature sensor error so I tried connecting a new sensor but just let it hang so the computer thinks the engine is always cold. Right back to the P2646 with the temperature sensor connected.
So I'm looking for an explanation.

 

[07lmnt]

When the ECM sees a coolant temp error, it most likely will not go into VTEC.

You mentioned oil pressure, where did you tap in to take this measurement, and what was the PSI?

 

[wingingEd]

I honestly don't care if it doesn't go into VTEC
Oil pressure at the sender near the oil pressure is 19 at idle, and 48 at 3k rpm.
I'm considering running a mechanical temp gauge and just leave the electronic one disconnected.

 

[07lmnt]

You have to measure the oil pressure at the VTEC solenoid. Using a T leave the oil switch in place. When it goes into VTEC at 2200 rpm, you should have min 35 psi. It should go back to 0 at 1800 rpm. Do this while driving and fully warmed up, it will not go into vtec unless driving. If this part is working, report back and will walk you through the next test.
If you leave the ECM coolant sensor disconnected, it will set codes. I guess you dont give a sh*t about codes, but if you have to pass emissions it won't.

 

[Fleetw00d]

You might not care about VTEC, but the engine does; with the P2646 code set, the engine won't accelerate past about 3000 rpm which doesn't make the vehicle very drivable. Minimum oil pressure at idle is supposed to be 10 psi; 44 psi at 3000 rpm; so you're good there at least. You say you changed the spool valve - did you change the whole spool valve and switch assembly, or just the valve? If you remove the switch and can vary the pressure to it, check at what pressure it opens and closes.

 

[Kmead]

I bought a 2008 LX AWD in Nov 2019. As I have more cars than I should it sat until December 2020. When I bought it, it was suffering the dreaded 2646 code and at 187k miles was a ”as is” $3000 car from a local dealer.

I finally started driving it and had tried a few of the standard approaches to resolving the problem. Oil change. Oil flush with oil change. Clean the two primary mesh filters (the one behind the PS pump was effectively completely clogged). Sadly to no avail. Before I had bought it the dealership had replaced the spool valve assembly with a cheap aftermarket version which had no effect on the issue.

So after driving the car periodically for a month with a Bluetooth OBD2 to reset the system at each long red light to at least accelerate away near a rate of normally running cars. I bought two OE parts, a Honda supplied spool valve assembly and a VVT solenoid.

The install of the spool valve went well, the VVT Solenoid um not so much. After removing the 10mm bolt I went to rotate and pry the unit out which resulted in the electrical solenoid part in my hand and the primary metal body still inside the engine. Ugh. The center piston when I went to remove it had a lot of resistance and could be canted slightly to engage a rib inside the body which sparked the idea of using it to pull the body of the solenoid out rather than threading something in, which happily worked well. Cleaned out the remaining oil, grit and guck using a foam brush wrapped with a rag which elicited a fair amount of crap on the successive rags. Examining the old unit revealed a part which had been in the car since new, filled with the peculiar grit that one finds in the screens and the varnishy buildup one sees on metal parts over time. The new one installed, electrical connections made, engine started and checked for leaks. Good to go.

Reset the system and took off. Got to the main road and gave it some gas, went up through first, second and third and the dreaded lights went on. Sigh. Pulled over and reset the system. Took off again and another mile up the road again the lovely warning lights. I pulled over, reset it again and the drove off rather gingerly feeling rather defeated. Pulled away from a stop sign and tried accelerating hard when suddenly the engine started pulling hard like my other Element does. No lights, proper acceleration and the rest of the drivetrain is now working properly.

It’s been a week now and hopefully the engine will continue without the plethora of lights and only 2800 rpm available. I am tempted to pull the VVT Solenoid to see about cleaning any remaining detritus which has made its way to the unit.

So a suggestion to others, consider replacing both assemblies along with cleaned screens. Obviously no guarantees, and only time will tell but so far so good.

Thanks to all who have shared your experiences with this problem. All the best.

 

[Fleetw00d]

You might consider something like SeaFoam in the engine prior to your next oil change, sounds like you may still have a fair amount of sludge floating around in the system.

 

[Kmead]

You might consider something like SeaFoam in the engine prior to your next oil change, sounds like you may still have a fair amount of sludge floating around in the system.

I have run a high detergent oil flush from NAPA through it so far, before the next change (after a few tanks of gas) I will do it again. I may try Seafoam in the gas and some in the oil at the same time.

Marvel Mystery oil is a high detergent oil as well and can help with build up. Automatic transmission oil is another high detergent oil which can also be used.

Thanks

 

[Fleetw00d]

After you do so, you may want to check the rear screen again just to see if you've dislodged more stuff. If it is clogged again, consider the same for the front screen.

 

[AWD]

I have run a high detergent oil flush from NAPA through it so far, before the next change (after a few tanks of gas) I will do it again. I may try Seafoam in the gas and some in the oil at the same time.

Marvel Mystery oil is a high detergent oil as well and can help with build up. Automatic transmission oil is another high detergent oil which can also be used.

Thanks

See Honda's bulletin on this code attached.

 

[wingingEd]

Solved (so far). I was getting p2646, p2647, and p1009. As you can see by my post above, I did everything I could think of. What worked for me (again, so far) was to change the oil again using 10w30. My guess is, with almost 300k miles and evidence of prior neglect, my engine is about gone and the thicker oil is temporarily helping to maintain oil pressure at higher rpm.

Time to replace the engine!

 

[AWD]

Solved (so far). I was getting p2646, p2647, and p1009. As you can see by my post above, I did everything I could think of. What worked for me (again, so far) was to change the oil again using 10w30. My guess is, with almost 300k miles and evidence of prior neglect, my engine is about gone and the thicker oil is temporarily helping to maintain oil pressure at higher rpm.

Time to replace the engine!

10W30 or 5W30 oil?

 

[Fleetw00d]

I think you could run a long time on 5W30 or 10W30. My daughter is doing the same thing at only 220,000 miles (she only has problems after extended highway driving particularly in warm weather). Dealer confirmed low oil pressure at idle; the pressure drops low enough to trip the code when you back out of the throttle and engine speed (and oil pressure) drops before the VTEC attempts to shut off (I think that is the scenario). I'd probably even have her try 5W40 before swapping the engine. I have a spare engine that I need to get around to rebuilding for when that time comes.

 

[wingingEd]

I used cheap 10w30 just to test. So far... no errors.

 

[07lmnt]

I've used 5W30 mobil 1 since brand new, no problems at all. I get it for free is the only reason. The Acura 2.4's use it too.

 

[philharmonic]

I think you could run a long time on 5W30 or 10W30. My daughter is doing the same thing at only 220,000 miles (she only has problems after extended highway driving particularly in warm weather). Dealer confirmed low oil pressure at idle; the pressure drops low enough to trip the code when you back out of the throttle and engine speed (and oil pressure) drops before the VTEC attempts to shut off (I think that is the scenario). I'd probably even have her try 5W40 before swapping the engine. I have a spare engine that I need to get around to rebuilding for when that time comes.

Why not try 20W-50 before installing a new engine? Or ream out your oil filter, so it doesn't have any filtration stuff in there and maybe pick up a few psi's and get another 20,000 miles out of the engine, you might have to change the oil every 2,000 with no oil filter, but hey, you're going to scrap it anyway. Or put an extra quart in there. Or pull oil pan and change out the rod bearings off and even the main bearings, that usually gets you a bunch of oil pressure. Just thinking outloudl.

 

[Fleetw00d]

Why not try 20W-50 before installing a new engine? Or ream out your oil filter, so it doesn't have any filtration stuff in there and maybe pick up a few psi's and get another 20,000 miles out of the engine, you might have to change the oil every 2,000 with no oil filter, but hey, you're going to scrap it anyway. Or put an extra quart in there. Or pull oil pan and change out the rod bearings off and even the main bearings, that usually gets you a bunch of oil pressure. Just thinking outloudl.

I did put new rod bearings in. I should have figured out a way to change the crank bearings. I wonder if I had unbolted the bottom of the block whether I could have gotten enough relief (letting the crank sag some) to be able to remove the upper crank bearings.

 

[bmhendri]

Hello!
my element slides into limp mode and I can't seem to fix it. (It will not increase higher than 3K RPMs when this is occurring). It doesn't always do it and sometimes cutting it off for a few minutes will reset it. I have replaced the vtec assembly (solenoid), the oil pressure censor, and the pigtail wiring harness. Any idea what else it could be? I can drive it around like that but it can be dangerous if I need to drop a gear to accelerate quickly.
I actually replaced the original engine because I couldn't get the old one from sliding into limp mode when driving...Then, it had a head gasket issue and under normal conditions I would have had that fixed as well BUT I never could get to the bottom of the limp mode issue.
Now, I have had the new motor installed and STILL it slides into limp mode. I'm frustrated at the money invested and still I can't figure out the limp mode issue. I find it hard to believe a newer motor (100K miles) would have the exact same issue. Could it be electrical or a computer issue?? I have no idea at this point.

Any bright ideas???

PS. I own 4 elements and this is the only one giving me trouble but I have had 2 others with limp mode problems that were fixed and never did it again.

 

[07lmnt]

Hello!
my element slides into limp mode and I can't seem to fix it. (It will not increase higher than 3K RPMs when this is occurring). It doesn't always do it and sometimes cutting it off for a few minutes will reset it. I have replaced the vtec assembly (solenoid), the oil pressure censor, and the pigtail wiring harness. Any idea what else it could be? I can drive it around like that but it can be dangerous if I need to drop a gear to accelerate quickly.
I actually replaced the original engine because I couldn't get the old one from sliding into limp mode when driving...Then, it had a head gasket issue and under normal conditions I would have had that fixed as well BUT I never could get to the bottom of the limp mode issue.
Now, I have had the new motor installed and STILL it slides into limp mode. I'm frustrated at the money invested and still I can't figure out the limp mode issue. I find it hard to believe a newer motor (100K miles) would have the exact same issue. Could it be electrical or a computer issue?? I have no idea at this point.

Any bright ideas???

PS. I own 4 elements and this is the only one giving me trouble but I have had 2 others with limp mode problems that were fixed and never did it again.

Did you read my post #465 above? Follow the diag I set up, and report back. There is no silver bullet for this code. It's a case by case repair. If you have non Honda vtec solenoid and switch get rid of that.