Never Ending P0400 & P0026

Hello and thanks for taking the time to read this. I have a 2007 Legacy 2.5 SE that I am just about ready to get rid of! It was a Great car until about 110,000 mile mark, but has been a pain since.

 

I've been battling a P0400 CEL for about six months now and a P0026 for about a month. I don't know why, but the codes always come in this pair the last month. I've run out of ideas and I've fixed every part that I know of.

 

For the P0400, I've replaced:

-EGR valve

-EGR solenoid

-Cleaned the TB/ EGR passages/EGR tube with seafoam deep creep four times.

-Used a speedometer cable to clean the passages each time.

-Checked all vacuum tubes for cracks or blockages (none found)

-Checked PCV valve (works)

-Replaced missing block->frame grounds (probably not related )

 

The EGR debacle started when I noticed a lack of power and my fuel mileage in the 15's. The car runs and idles great, fuel mileage is back to normal.

 

In regards to the P0026, ironically enough I was getting a P0028 and decided to replace the vvt solenoids and oil pressure sensors on both sides. The p0028 went away, but now I'm getting the P0026.

 

For the P0026 I've done the following:

-Replaced the VVT solenoids and oil pressure switches

-Checked the resistance of both parts on both sides

-Passenger & driver side oil switches were both ~0.6ohm

-Passenger side vvt solenoid ~ 3.8ohm

-Driver side vvt solenoid ~8.0ohm

-Did no use any sealant or tape on the oil pressure sensor threads

-Did not notice any frayed wires.

 

I have to commute 80+ miles on a regular basis and would like my cruise control to work again! If i clear the codes, it usually takes about 50 miles or so before the codes return, always together. I haven't gotten any other codes thus far. I have no idea what to do next and don't want to dump the car, but I cannot spend every weekend trying to fix the problem to no avail. HELP!!!:confused::confused:

are any other lights flashing or just the steady CEL.

 

I think you may be confusing VVT with VVL, the EJ253 has static cams so it has no VVT to advance or retard timing

 

here is an thread from our outback friends

http://www.subaruoutback.org/forums/66-problems-maintenance/37825-engine-code-p0026.html

Did you use oem vvl switches? It might be time to check the wiring from the switch harness to the ecu.

are any other lights flashing or just the steady CEL.

 

I think you may be confusing VVT with VVL, the EJ253 has static cams so it has no VVT to advance or retard timing

 

here is an thread from our outback friends

http://www.subaruoutback.org/forums/66-problems-maintenance/37825-engine-code-p0026.html

 

Thanks for your reply. I have read the forum you linked to, and many many others. You are correct that I do have the systems confused, I think the term vvt is so common that default to saying that. As far as the CEL, it is always steady. At no point has it flashed at all.

Did you use oem vvl switches? It might be time to check the wiring from the switch harness to the ecu.

 

Hello, and thanks for your reply. I did not buy the OEM vvl switches, or at least I did not buy them from the dealer. The old and new switches looked identical besides corrosion and such. I'm going to switch the driver and passenger side switches next weekend and see if the code moves. Any suggestions on where to start with the wiring? The wires near the switches look like they are intact.

Was there corrosion on the connectors? It could be something simple. Make sure the pins in the connectors are clean and intact. You could have pulled a wire out of a connector when replacing the switches. I would recommend getting 2 new switches from the dealer as well. I vaguely remember reading about it on Identifix when I had an 07 forester with the same code.

Was there corrosion on the connectors? It could be something simple. Make sure the pins in the connectors are clean and intact. You could have pulled a wire out of a connector when replacing the switches. I would recommend getting 2 new switches from the dealer as well. I vaguely remember reading about it on Identifix when I had an 07 forester with the same code.

 

OK, great. I really appreciate your input. I'm going work on the car when I get home on Friday and will report back. I didn't notice any corrosion on the wires, and they appear to be firmly in place, but I will look more closely.

Does anyone know what the diameter of the EGR port on the driver's side head is supposed to be? Last weekend when I did carbon cleaning #4, I had the EGR tube off and gently inserted a small phillips screwdriver (#1?) into that hole. It barely squeezed in there. I didn't even think twice that that could have been a problem. Ill have to find a mirror to look tomorrow, but does that sound like the port is occluded? By feel it felt like a symmetrical conical shape but I cant be sure. It would seen odd that such a large diameter tube is required for such a small outlet of gasses from the engine. Idk, I think im going crazy at this point

So I wasn't able to make it to the dealer in time last weekend, but I think I'm going to replace the EGR and VVL oil switch. It seems unlikely, but perhaps both units are faulty. I'm going to buy the OE ones from the dealer and see what happens. Maybe I'll replace the smaller PCV hoses too. No sure what else it could be. Wish me luck.

There's two vvl switches so replace both. Apply a vacuum to the egr valve and if it opens, you know it's working properly. I don't know how large the hole is supposed to be but I'd assume the same diameter as the tube you removed.

There's two vvl switches so replace both. Apply a vacuum to the egr valve and if it opens, you know it's working properly. I don't know how large the hole is supposed to be but I'd assume the same diameter as the tube you removed.

 

Im only getting the code for the passenger side, I replaced both when I had the code for the driver's side! What a mess. Any suggestions on how to apply a vacuum to my EGR? Its just two ports, two bolts and an electrical connector, no vacuum hoses attach to it.

 

I was doing some city driving today and noticed that the engine was chugging when taking off from a standstill, idle bounced around just a bit, seemed fine above 2000 rpm. IM wondering if that could be a vacuum issue. No new codes to report. Also considering maybe the front O2 sensor needs replacement? Im definitely going to replace the pcv hoses, pcv valve/ oil switch tomorrow and maybe the front O2 sensor. I dont think the new EGR valve could have gone bad in three months.

So I made it to the Subaru dealer and purchased an oe vvl oil pressure switch and an upstream o2 sensor (on a hunch). Got everything back together, took it for a test drive and ...cel came back on . Just getting the p0026 this time, not the p0400 (hopefully done with that!) No idea what to do now. I tested both of the new vvl solenoids with a 12v power source last week and they function similarly. Im not sure where to go next other than replacing more parts.

Did you just replace the driver or passenger side switch? The p0026 is bank 1 which is the passenger side.

Did you look at diagnostic procedure in FSM? I attached screenshot from 2008, hope these will help.

 

http://legacygt.com/forums/attachment.php?attachmentid=253610&stc=1&d=1501905438

 

http://legacygt.com/forums/attachment.php?attachmentid=253611&stc=1&d=1501905438

 

http://legacygt.com/forums/attachment.php?attachmentid=253612&stc=1&d=1501905438

Thank you so much for the great information. I will read and digest that soon. Just another update, I replaced the PCV valve today, cleared the codes and went for a drive. Made it about 15 minutes without any codes, everything felt great. Was slowly accelerating onto the freeway, and the CEL came back on. Here's the confusing part, I drove home (couldn't rev above 4k in second gear, could in first?), parked in my driveway, Turned the car off, then did the sequence to have the dash show me the codes. It comes up P----. How strange. So I get my cable out and check for any stored codes and none are stored or pending! Currently idling w/o any codes, will go for a second test drive soon and see what happens.

So...the codes came back the same day. I ended up switching the vvl solenoids and the code moved. I sent the offending solenoid back for a warranty replacement. I can say that the p0026/0028 has disappeared and has not returned for several weeks. As for the original problem (p0400), its still there. I think I'll replace the EGR valve one with the Subaru version in a month or so, it must be faulty. I put the original egr valve back on and I cannot tell any difference, so maybe they are both bad.

So, an update to the still remaining (and probably boring) P0400 is that the code cleared itself after a lot of freeway driving (I may have gotten to freeway speeds before the engine was completely warm), but turned back on the next drive cycle, without any noticeable signs. I read the code, and it was again P0400 along with P1492, which is a low voltage condition in one of the EGR circuits (as I understand it). My best guess is that this is more evidence that the new EGR is faulty. Thoughts?

 

I read the FSM, and the manifold absolute pressure is within the normal range. I'm hoping to have the money to buy an OE EGR next month, and I hope that this is the only part I need.

 

Thanks for all the help so far!

I got the switch part from Amazon for $20 and the p0026 code went away. First time that the check engine light and flashing cruise light haven't been on a very embarrassingly long period of time. Five minute job and 15/16 deep worked fine vs buying/locating my 24mm deep which i swear came with the set.

 

 

 

https://www.amazon.com/Subaru-Genuine-25240AA060-Switch-Assembly/dp/B00E1J4OVM#customerReviews