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Discussion Starter #1
Hello Outback Experts...

I have a 2006 OB 2.5i with about 115k miles on it. Over the past year, I've been getting an intermittent Check Engine light. It goes like this...

I'll be driving along (usually at freeway speeds, but not always) then exit the freeway or come up to traffic requiring me to slow down (just take my foot off the accelerator).
After a few seconds, the check engine light will come on, the Cruise control will start blinking and the accelerator will not respond. The idle will sit at about 2000 RPM.
I usually coast to a stop, turn off the vehicle and wait. If I restart it right away, it will start fine, but the accelerator won't work. I usually wait until I hear a pair of 'clicks' from
the glove box area. Then I try to restart it. It won't start the first time, just cranks.
The second time, it will restart, accelerator will work fine, but the check engine light is on and the cruise control will flash.

The CEL will stay on for two more driving 'sessions'. After that it will go back to normal.

I don't have a code reader, can't really afford one, and the Autozone's in California are prohibited from offering that as a service.:(

This has been happening at an increasing rate. I did have the timing belt replaced a few months ago, but.. not related I don't think, or is it?

Anyone else have this problem or am I just 'lucky'? What could it be?
:confused::confused::confused:

Thanks for any help...
 

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This one is cheap and more than good enough to reliably read your codes:

[ame]http://www.amazon.com/Autel-MaxiScan-MS300-Diagnostic-Vehicles/dp/B001LHVOVK/ref=sr_1_1?s=automotive&ie=UTF8&qid=1351327603&sr=1-1&keywords=Autel+obdii+code+reader[/ame]



Pretty hard to speculate without a code.
 

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I have a truck that was giving me all kinds of different codes. I couldn't afford to even begin to start replacing all the things the codes were telling me that were wrong. After testing this and testing that over the course of about six weeks, I finally discovered, quite by accident, that the ground bonding straps in certain locations were corroded to the point of failure (and intermittent failure).

With a battery jump cable clamped to the negative of the battery, I went around and tested everything metal. I found that the vehicle's frame was not bonded to ground, nor was the engine block. About $30 worth of battery cables with an eye on each end and several stainless nuts & bolts with star washers and about three hours and I had everything bonded again to ground, PROBLEM GONE!

That was last spring, or so, and there hasn't been an issue since!

Even my mechanic was stumped! I knew when I touched the negative battery cable clamp to the frame with the ignition on and got a spark that I was on to something! I had to clean each spot I secured new bonding cables to with a wire brush on a drill to get down to bare metal. After bolting the cable ends, I sprayed them each with Rustoleum, then when that dried, I sprayed them with Lithium Grease.
 

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The symptoms (fixed engine rpm, lack of accelerator response, CEL on and Cruise flashing-- the latter is normal when the CEL comes on), are indicative of the engine control unit going into "failsafe" mode due to a detected fault, usually related to safety, emissions, or potential for damage to the engine or transmission. The OBD code or codes will provide clues as to the cause. Even if the CEL has gone off, many codes are retained in memory for up to 40 driving cycles, so there's still a chance to see what they were and possibly take preventative action.
 

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Great post - thanks. These subies can run a long time in harsh conditions. Being aware of rust and grounding for proper operation of all the electronics nowadays sounds like it's very important.
 

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Discussion Starter #8
Even if the CEL has gone off, many codes are retained in memory for up to 40 driving cycles, so there's still a chance to see what they were and possibly take preventative action.
Wow, I had thought it had to be on to get a CEL code out of it. I had originally thought this, but one of my 'mechanic' friends told me that if the light wasn't on, I was out of luck.
 

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Discussion Starter #9
K7ELH,

You should be able to display the codes on your dash. Try following the instructions at http://www.subaruoutback.org/forums/99-do-yourself-illustrated-guides/19053-05-09-how-read-diagnostic-trouble-codes-dtcs.html

73 de KR2D
KR2D,

Nice! I will have to try that when my wife gets home (she loves driving my car. She has a lead foot and can't do much with her Rodeo).

Now, what does VDCCM stand for? The others I get (Electronic Control...etc.).

Thanks & 73s

Eric K7ELH

PS. maybe we should get a ham Outback club together? Out of the 60 members of my local ARC, there are 11 Subarus (mostly Outbacks).
 

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Now, what does VDCCM stand for? The others I get (Electronic Control...etc.).

PS. maybe we should get a ham Outback club together? Out of the 60 members of my local ARC, there are 11 Subarus (mostly Outbacks).
VDCCM is Vehicle Dynamics Control control module. You probably don't have VDC.

Subarus are well represented at my local ARC, too. The reaction is great when I drive up the forest service road to our favorite VHF contest site: "You got here in that??!!" One guy bought his Outback because mine made it up that road - he wanted one to replace his old truck, but wasn't sure an Outback would get him up the hill.
 

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Wow, I had thought it had to be on to get a CEL code out of it. I had originally thought this, but one of my 'mechanic' friends told me that if the light wasn't on, I was out of luck.
Codes that are related to more serious/critical faults, especially those that result in the ECM reverting to a failsafe status, will be retained in memory for the extended period.

The procedure that ron917 suggested above does work, although I found it somewhat tricky to get the timing right. But it does serve quite adequately.

That Autel reader on Amazon is quite a good deal -- I have one that's similar (under another brand) but paid much more. It's the type of tool that's easy to keep in the car and have handy at all times.

I also use FreeSSM and RomRaider Logger (thread linked above) -- FreeSSM will read and clear codes as well as display ECM and TCM operating parameters; the RomRaider Logger displays and records parameters (in a spreadsheet file), but does not read/clear codes. They are both free computer programs, and only require the inexpensive interface cable to work with your car.

p.s. 73 from VE3-land.
 

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Discussion Starter #13
Okay, I went and borrowed a code reader from a friend. Here's what I got.

P0026 Intake Valve Control Solenoid Circuit Range/Performance Bank 1
P0028 Intake valve Control Solenoid Circuit Range/Performance Bank 2

The reader said that there were 3 faults but one was N/A. These were the other two...

Would either of these cause the problems I am having?

Eric, K7ELH

PS. We should start a thread about Ham radio and Outbacks!
 

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Discussion Starter #14
Subarus are well represented at my local ARC, too. The reaction is great when I drive up the forest service road to our favorite VHF contest site: "You got here in that??!!" One guy bought his Outback because mine made it up that road - he wanted one to replace his old truck, but wasn't sure an Outback would get him up the hill.
Nice! A Convert!...

I saw a few vids on this board of an Outback doing some SERIOUS offroading, but I myself would never do that. I need my car daily!
 

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P0026 Intake Valve Control Solenoid Circuit Range/Performance Bank 1
P0028 Intake valve Control Solenoid Circuit Range/Performance Bank 2

The reader said that there were 3 faults but one was N/A. These were the other two...

Would either of these cause the problems I am having?
According to the FSM, I don't think so. They would trigger a CEL, and remain in memory for 40 cycles, but there's no fixed throttle failsafe indicated in the FSM that's associated with these faults. There could be poor idling, but others have had the same code(s) without symptoms being reported. See, for example, this current thread: http://www.subaruoutback.org/forums/65-parts-accessories-performance/49338-oil-pressure-valve-solenoid.html, and search the forum for other threads about the codes -- there's a few.

That said, there are some faults that, on their own, will trigger a CEL but not instigate failsafe conditions; however, if at the same time there's more than that one malfunction, it will do so. (Some problems with the drive-by-wire accelerator are among these.) So perhaps, even if the FSM doesn't say so, it might be that if two related codes, such as the two you have, are registered, the ECM does go into failsafe mode.

Or, could it be caused by that N/A third code? How long has it been (drive cycles) since the fixed throttle symptoms were experienced? Could that 3rd code have been cleared?

Also, I don't recall any cases where the variable valve lift mechanisms triggered codes for both sides (left and right) at the same time.
 

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According to the FSM, I don't think so. They would trigger a CEL, and remain in memory for 40 cycles, but there's no fixed throttle failsafe indicated in the FSM that's associated with these faults. There could be poor idling, but others have had the same code(s) without symptoms being reported. See, for example, this current thread: http://www.subaruoutback.org/forums/65-parts-accessories-performance/49338-oil-pressure-valve-solenoid.html, and search the forum for other threads about the codes -- there's a few.
Well, I just drove to my sister's store and got the poor idling. Never happened before. Just started after I read the codes! But I didn't get a CEL.

That said, there are some faults that, on their own, will trigger a CEL but not instigate failsafe conditions; however, if at the same time there's more than that one malfunction, it will do so. (Some problems with the drive-by-wire accelerator are among these.) So perhaps, even if the FSM doesn't say so, it might be that if two related codes, such as the two you have, are registered, the ECM does go into failsafe mode.

Or, could it be caused by that N/A third code? How long has it been (drive cycles) since the fixed throttle symptoms were experienced? Could that 3rd code have been cleared?

Also, I don't recall any cases where the variable valve lift mechanisms triggered codes for both sides (left and right) at the same time.
Okay, so now I am even MORE lost AND it's running crappy. Just great. :rolleyes:
 

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while it's difficult to be certain about anything, I would put the following near thge top of a lis of possibilities;

bad or questionable or intermittent oil issue due to;



odd problem with oil filter

odd problem with oil pump

partially block oil screen in banjo bolt for avcs w'ever system.



Odd electrical problem;



bad ground connection

bad/corroded cable
 

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The week grounds is a good start. Check your battery amperage output and conductivity to the block.

Check your oil level.

Clean the throttle body with "Throttle Body Cleaner" specific to electronic throttle bodies. If you have the oil/carbon build up on the surface of the throttle and body itself, it throws off the voltage feedback to the computer because the plate position won't match what the computer wants. I get a lot of dirty T-bodies that cause similar codes and issues on a number of different makes and models. The manufacturers should redesign the crankcase ventilation system to feed after the throttle.

Make sure there isn't any dirt or debris build up on the accelerator pedal position sensor and that it is still connected tight.
 

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The two simultaneous VVL-related codes are unusual -- they are two separate systems on opposite sides of the engine -- which suggests something common.

There's one report here (did a search for "P0028") of both codes occurring at the same time due to low oil (despite there not being a low oil pressure warning light on). In the present case the two codes are in memory but, it appears, not active (the CEL is off). So they might be from some earlier incident (within the last 40 drive cycles). But do check the oil level.

I did some further searching of the FSM. Turns out the only indicated instances where a fixed throttle failsafe is triggered is when there's a problem in throttle control functions. I'm wondering if the third "N/A" code is related. In the first post there's reference to waiting for two clicks from the glove box area to restart the engine. The throttle control relay is located there (extreme right side of the dashboard). Also, the throttle plate's mechanical "rest" position is at roughly 2000 rpm, so this is consistent with the ECM disabling the throttle by de-energizing the throttle control relay.

As suggested, perhaps remove and re-install the connector at the accelerator pedal a few times to ensure that the contacts are good. But it might be the accelerator pedal assembly itself. See, for example: http://www.subaruoutback.org/forums/66-problems-maintenance/24906-code-p2138-throttle-position-sensor.html, and, http://www.subaruoutback.org/forums/66-problems-maintenance/39533-please-help-stuck-open-throttle-2500-rpm.html.

I'm almost of a mind to suggest clearing the codes (many code readers have a "clear code" function) and then see what happens. Keep a copy of the instructions about reading the codes (post #7 above) or a code reader handy in the car. In the event the CEL comes on again, and especially if the accelerator stops functioning, read the codes right away. Hopefully that will confirm the source.
 
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