Engine Code P0026 - Subaru Outback - Subaru Outback Forums
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post #1 of 11 (permalink) Old 08-11-2011, 02:19 AM Thread Starter
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Engine Code P0026

I have a 2010 (bought in September of '09) Outback 2.5i Premium with 51,xxx miles on it. Yesterday, I made the 45 mile drive into work without any problems. The car sat for 10 or 11 hours and when I went to leave, I had the following warning lights:
  • Check Engine - steady
  • Vehicle Dynamics Control - steady
  • Cruise - flashing
  • Brake (parking) - flashing

I checked all my fluids - no problems. Visually checked the engine bay and the undercarriage - no problems. So, I made the 45 mile drive back to town where my hotel is. I stopped at Autozone and had a scan done. It kicked back:

P0026 - Intake Control Valve Solenoid Circuit, Range/Performance Bank 1

Possible Causes: open or short circuit, poor electrical connection, faulty intake valve control solenoid.

Well, I couldn't do anything with it at this point (7pm already, nearest dealer was another hour away). So, after eating dinner I went through the engine bay and disconnected and reconnected almost every wiring harness I could find. I started the car up, it also happened to be the third cycle after the warning lights came on, and everything cleared. No problems today going to or returning from work, so who knows.

Also, I recently had the ECM re-flash to update the emissions control system. I have noticed a slightly rougher idle, but it is also intermittent. I have heard of some other people having the same issue: brought in for cat recall... new code found (P0028?)

Now, this is partly for my education and illustration for everyone else. Here is what I think the intake valve control solenoids are:







There are two, one mounted at the front of the driver side of the piston block and one mounted at the rear of the passenger side.

So, if anybody has any opinions, corrections, more information please feel free to share!
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post #2 of 11 (permalink) Old 08-11-2011, 09:36 AM
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You've identified the VVL solenoids correctly (1st photo, sloped, with the blue connector). Each solenoid is paired with a pressure sensor -- the vertical part with the white connector. The bank 1 solenoid is the one the passenger side at the rear.

Even though the CEL has gone out (after three drive cycles), the code might still be stored in the memory.

The linked threads, unfortunately, don't seem to provide a clear conclusion whether or not the code is related to the reflash. There are few reports of post-reflash impacts.
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post #3 of 11 (permalink) Old 08-12-2011, 04:55 PM Thread Starter
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Thanks plain OM.

I can in no way confirm that the rough idle or the code is due to the re-flash, just a series of events that is slightly suspicious.
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post #4 of 11 (permalink) Old 10-31-2013, 04:53 PM
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Travis,
I own a 2009 forester, and had something very similar happen. I had the check engine steady, the dynamics light steady and the cruise control flashing. I did not get the parking light flashing.
When it first happened I was accelerating onto the freeway, and the engine seemed to cut in and out for about 20 seconds like it was misfiring, then was fine. All the lights were back to normal when I drove home that evening.
I checked the code, and it was a P0026.

What I find intersting is that I had just had the catalytic converter recall done about 2 days before that. I understand they also reprogrammed the engine control then.

I think this issue must be related to that somehow.
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post #5 of 11 (permalink) Old 10-31-2013, 06:42 PM
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I haven't identified a definite connection between re-flashing and the appearance of the VVL control codes (P0026, P0028) shortly thereafter. However, the new software might have more stringent requirements for the pressure sensors (switch). If the resistance of the sensor contacts is too high, the ECM will interpret this as an "open" sensor when it should be closed. I believe this is a common cause of the two codes -- deterioration of the sensor internal contacts.

See this thread: Variable Valve Lift oil pressure switch resistance

If you have a digital multimeter that reads Ohms (resistance), measure the resistance between the pressure sensor contact and ground. It might be too high. This can also be an intermittent situation, with the resistance sometimes being too high.

To get a better idea of what might be happening inside a typical pressure sensor switch, see: Oil Pressure Sensor Switch – how it “clicks”
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post #6 of 11 (permalink) Old 11-01-2013, 03:54 PM
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Thanks for the reply. I may dig into it this weekend. I think you are right about the new software having more stringent requirements. Another possiblility is that the computer has to re-calibrate itself once it thinks the sensor has changed.

When it was at the dealer, they said they drove it for about 10 miles to give the computer a chance to recognize the new cat converter. Maybe something like that also happens with the sensors it is complaining about.

Now I have to figure out why my tire pressure warning goes on and off intermittemntly. All 4 tires are at 31 PSI. I'm guessing one of the sensors in my tires is flaking out.
Dave
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post #7 of 11 (permalink) Old 11-01-2013, 05:49 PM
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Quote:
I may dig into it this weekend.
Might want to search the forums here for the two related codes P0026 and P0028.
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post #8 of 11 (permalink) Old 11-01-2013, 06:15 PM
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I just read that first thread you linked to, where the sensor responds to oil pressure. As it happens, I just changed my oil and may have overfilled it slightly. Maybe that set off the warning.
I think I will spend some time searching the forum as you suggest. Lots of valuable information here.
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post #9 of 11 (permalink) Old 05-31-2014, 12:12 PM
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P0026 in 2009 Subaru Outback

We have the same issue. Highway driving when we saw the flashing-Cruise-Control/solid-CEL/solid-Traction-Control trio. A call to a dealer didn't help much, basically said "you have some problem" - though that may or may not have been a service associate.

This was my first real issue with the car, so some googling was in order. I saw about getting a code read, and luckily for me there are a few gas station/service stations in the area. One did a code read and it gave P0026. He basically said "it may clear itself, give it a good 30 mile drive - if it clears, you're good - if it doesn't clear, bring it in."

The main reason why i'm posting is that I did have the rough idle after they cleared it. There was nothing done to the car - no ECM reflash, just a simple drive.

So, i'll leave this here for updates.
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post #10 of 11 (permalink) Old 06-26-2014, 10:52 PM
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Okay, I'm having a similar issue. Had an oil change, and the kid (tech) didn't let it sitfor thirty seconds before driving it into the bay and dropping the plug. Oil was "changed" in about five minutes. (BIG red flag.) Drove about 70 miles, and was onhighway when I felt a soft "pop", and lost torque. Engine acted like it was trying to die, but didn't. Idled very rough, though. Took it to auto parts store to get ECM codes read, and I got the P00026 and 28, as well as misfire in cylinders 3 and 1. Checked the oil, and it was as dirty as 3,000 mile oil, easily. Not to mention, about 3/4 of an inch overfilled. I called the service station to see if they had checked the PCV, since that seemed to be how the engine was "acting", and an overfill might cause it to break. The kid told me I had been running my engine with no oil in it, because only a quart came out. (Gee, could it be that the rest was still in the block?) I asked how that could be, and he explained that it was "leaking, dripping all over from somewhere up top". Interesting, since there was no leak, and I park in the exact same spot, day after day, and no oil spots. I could eat off the top of that engine. The only oil I was able to see was some "blowby", probably built up since the car rolled off the line. No drips. None. He then explained that since I "ran it without oil, it can't take the pressure". (Apparently, my gender precludes any knowledge I have of basic physics, thermodynamics, or engines.) He kept insisting that my engine had "seized", making some comment about, "Well, now that it won't turn over...", and, "Well, you ran it without oil. It's seized, now". (As I'm talking to him with the engine idling, for crying out loud...)
Long story short, replaced plugs, wires, coil pack, PCV, all to no avail. Worried about my rings. Any ideas?
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