Subaru Outback Forums banner

1 - 20 of 25 Posts

·
Registered
2000 Outback 2.5L 5 Speed, 2014 Outback Premium 2.5L CVT
Joined
·
153 Posts
Discussion Starter #1
I have a 2008 Outback that has had a lot of problems, I hope you don't mind reading about them as I'm hoping the history of this car will help diagnose the problem and decide where to go from here.

I bought the car 3 years ago from a local dealer, it had 109k miles on it then, it now has 132k. They told me they had just replaced the head gaskets and timing belt, and I could see new gaskets in there. The second day after we bought the car it started missing badly, took it back, they had their mechanic replace the plugs, wires, and coil pack, missing problem solved. Not too impressed with their mechanic if he didn't do at least the plugs and wires when doing head gaskets.

About 8 months later it started overheating and burning coolant, I took it to my own mechanic who has worked on my wife's family's cars for years and had done work on my 2000 Outback before with no problems. He diagnosed it as bad head gaskets. I was pretty annoyed with the dealer and their mechanic at this point, but since he had the car I just had him replace the gaskets.

6 Days after we got the car back we were on a trip, it died. Had it towed back to this mechanic, the bolt that holds the timing belt tensioner in place had broke, and I'm sure you know what happened then. He repaired the car at no charge to me, he had the heads repaired at a local shop that he also works for, I know several valves had to be replaced.

After we got the car back it ran great, however it burns about 1 Qt. of oil every thousand miles, and at times I would see blue smoke at startup, my guess was valve guides didn't get replaced properly, but just a guess.

Since then I have replaced the PCV valve as I've read that can cause oil consumption, and I think it has decreased some, but I haven't been able to actually measure it yet as I've lost some oil due to other failures.

Also for the past month I've noticed some spark knock happening, the interesting thing is it doesn't happen during acceleration or going uphill like it usually would, it happens when on level ground maintaining speed or more often on a light downhill grade, but not downhill enough to coast. I've tried 89 and 91 octane fuel and it seems to go away. I've also just bought a tank of 87 octane gas of a different brand, and I don't think I've heard it but I've only driven about 100 miles so far and that isn't enough to confirm it is gone. It is very faint when I do hear it, the radio and moderate volume will drown it out, but it is there.

I'll list some other repairs done,

I had to replace the passenger side Oil pressure sensor, the one for the valve timing, it started leaking oil.
I just replaced the valve cover gaskets for leaking oil, along with the plugs and wires.
I had the heater core replaced by my current mechanic.
I've had some other failures but they are not engine related.

Now on to the code. I've read here that this can often be a bad catalytic converter, but I've read that it can be caused by other thing as well. So my questions are,

What usually causes this and where should I start?

If I do have a bad valve guide/guides causing oil consumption could this have caused the catalytic converter to fail and just cause the same thing if I get the converter replaced?

If I continue to drive the car as is am I causing any major damage to anything else?

There are 2 converters, is it usually one or both?

Thank you for reading all of this, any advice you can give me on any of these problems would be appreciated.
 

·
On the Super Mod Squad
2002 Pair: 3.0 VDC Wag & 2.5 Limited Sedan
Joined
·
26,197 Posts
your other problems may have laid some extra soot/ oil on the rear o2 sensor and shorted its life.

replace it with a denso branded one. (bosch don't react like OEM).

I would buy one from Amazon or RockAuto. (local shops like to charge too much on these sometimes).

___________

I have had p0420 bouts two times on my EJ251 car. each time fixed with a new Denso rear o2 sensor.

(got 118,000 on it now, replaced at 65,000 and 100,000). runs on regular 87 gas. head gaskets done from external oil leaks around 95,000)

______


my EZ30 has all the original sensors on it, 128,000 miles and always on 93 octane o2 sensors are wear parts though,...but that car has a lot more going on with it in every way.
 

·
Registered
2000 Outback 2.5L 5 Speed, 2014 Outback Premium 2.5L CVT
Joined
·
153 Posts
Discussion Starter #3
Thanks, I like the price of an O2 sensor a lot more than the Catalytic Converter, I'll certainly try that. I've had better luck lately using OEM parts, any reason not to just order that? And just to confirm, it is the farthest back sensor correct?
 

·
On the Super Mod Squad
2002 Pair: 3.0 VDC Wag & 2.5 Limited Sedan
Joined
·
26,197 Posts
Thanks, I like the price of an O2 sensor a lot more than the Catalytic Converter, I'll certainly try that. I've had better luck lately using OEM parts, any reason not to just order that? And just to confirm, it is the farthest back sensor correct?
Denso is great and spec'd the same as OEM, and maybe HALF the price of the OEM. (and maybe Denso = OEM).

and yes the furthest one back. rockauto would call it "downstream"
 

·
Registered
1999 30th Anniversary Legacy Outback DOHC 2.5L 4EAT, 2008 Impreza WRX 2.5L 5MT, 2008 Impreza Wagon 2.5L 4EAT
Joined
·
1,224 Posts
How many O2 Sensors does your car have? I know the older ones had two and some newer ones have more. I had a P0420 code on cars with only two O2 sensors and was able to get rid of it with a drilled out spark plug extender (99 and 03). I don't know if this will work on newer cars.

Generally P0420 code can be set by exhaust leaks, bad O2 sensor or a bad cat. P0420 definately seems to be a common occurrance with some Subaru's
 

·
On the Super Mod Squad
2002 Pair: 3.0 VDC Wag & 2.5 Limited Sedan
Joined
·
26,197 Posts
How many O2 Sensors does your car have? I know the older ones had two and some newer ones have more. I had a P0420 code on cars with only two O2 sensors and was able to get rid of it with a drilled out spark plug extender.

Generally P0420 code can be set by exhaust leaks, bad O2 sensor or a bad cat. P0420 definately seems to be a common occurrance with some Subaru's
PZEV might have more. and I was reading those PZEV 2005-2009 cars also race their engines on first cold up,
to heat the cats up fast and to stop the stink. (like H6 ones do).

I would only add the "drilled out spark plug extender" spacer in after trying a new rear o2 sensor though. I heard a rumor that one is on my H4 car from 65,000miles -present day 118,000 miles. but no one looks to confirm. 0:) (california state smog people maybe the only ones paid to look for them in the US)

and I have seen those spacers sold as pre-drilled now hanging on garage walls in original shrink wrap.
(I would think every pro-garage has some ready or ready to drill).

edit: if I had to move to california. I would have a spacer installed, with a new Desno o2 sensor. and then only just before mandatory smog, (when the state people are looking), I would remove the spacer without unhooking the sensor from the car to do it. (so all the good data is saved)

...if the sensors are removed every once in a while they don't rust/corrode to stick in,...so a quick 5 minute thing swap such a thing on and off. (maybe with a little heat from a torch)
 

·
Registered
2000 Outback 2.5L 5 Speed, 2014 Outback Premium 2.5L CVT
Joined
·
153 Posts
Discussion Starter #7
How many O2 Sensors does your car have? I know the older ones had two and some newer ones have more. I had a P0420 code on cars with only two O2 sensors and was able to get rid of it with a drilled out spark plug extender.

Generally P0420 code can be set by exhaust leaks, bad O2 sensor or a bad cat. P0420 definately seems to be a common occurrance with some Subaru's
I'll have to get under the car and look, I'm not sure how many it has.

I'm not sure I follow what you do with the spark plug extender. Are you using it on the O2 sensor?
 

·
On the Super Mod Squad
2002 Pair: 3.0 VDC Wag & 2.5 Limited Sedan
Joined
·
26,197 Posts
I'll have to get under the car and look, I'm not sure how many it has.

I'm not sure I follow what you do with the spark plug extender. Are you using it on the O2 sensor?
it looks like a one inch hollow sleeve that goes over the o2 sensor.
it makes the inner tip of the sensor sit in a different place then it would ordinarily be. (1 more inch out).

so the thing reads a little different and makes it harder for the ECU to trip a p0420 code.
 

·
Registered
1999 30th Anniversary Legacy Outback DOHC 2.5L 4EAT, 2008 Impreza WRX 2.5L 5MT, 2008 Impreza Wagon 2.5L 4EAT
Joined
·
1,224 Posts
Essentially you remove the Rear O2 sensor and install this spark plug nonfouler (have to drill out the middle to larger diameter for O2 sensor to fit) then screw the Rear O2 sensor into it.



Some use this



Note that this mod may only work on older vehicles with just a front and rear O2 sensor. PZEV and newer vehicles use the rear O2 sensor differently and this may create more problems that it attempts to fix
 

·
Registered
2000 Outback 2.5L 5 Speed, 2014 Outback Premium 2.5L CVT
Joined
·
153 Posts
Discussion Starter #10
Interesting, thanks. So do you reuse the old o2 sensor or still replace it?
 

·
Premium Member
2001 VDC/SC One of a Kind
Joined
·
14,318 Posts
Have you read through my thread for P0420? I know its lengthy, but it shows in several post that its not always the CAT, sometimes its a little thing. The oil consumption can create flow issues for the CAT as well as increasing the carbon that the CAT can't reburn, like an engine running too rich. The CAT is designed for operation in specific tolerances for application. http://www.subaruoutback.org/forums/66-problems-maintenance/49537-p0420-diagnosis.html
 

·
Registered
1999 30th Anniversary Legacy Outback DOHC 2.5L 4EAT, 2008 Impreza WRX 2.5L 5MT, 2008 Impreza Wagon 2.5L 4EAT
Joined
·
1,224 Posts
Interesting, thanks. So do you reuse the old o2 sensor or still replace it?
I just reused the old one. I am not sure how much the rear O2 sensor works on the newer cars. I know on the older ones it was just used to validate catalyst efficiency and to set the Check Engine light if the cat was deemed to not be working efficiently.

There are some diagnostics you can use to validate cat efficiency (measuring temps of the forward and rear cats, checking live data, etc) so the spark plug non-fouler may not be a good fix for your car. I am not that familiar with the PZEV systems so take what I say with a grain of salt.

Definately read through the post mentioned above, it contains good info (even though it it long).
 

·
Registered
OBW H6 VDC, Tribeca, XT6
Joined
·
12,391 Posts
Sorry you've had such terrible experience with buying and repairing...what a mess. I cant' believe your resolve to keep at it!

P0420 is benign, I'd ignore it until you figure out your other issues. I've driven with P0420 codes for 100,000+ miles multiple times and a zillion other people have as well.

For oil consumption - install a Subaru PCV valve and run thicker oil, particularly when it's hot outside. I'd run as thick as you can essentially.

It's not uncommon for the piston rings to be the cause of oil consumption on these if oil changes weren't impeccable and it's seen overheating.

I had a P0420 code on cars with only two O2 sensors and was able to get rid of it with a drilled out spark plug extender.
What year were those Subaru's? I wouldn't recommend that on a 2008 unless he verifies that he can do it. Unlike older generations, the newer generations have a more complicated use of the rear sensors and aren't a good fit for the extenders. Since I don't routinely do it, I don't have mad data towards that end, so maybe he can find something else out but for a 2008 I don't think this is the ticket.
 

·
Registered
1999 30th Anniversary Legacy Outback DOHC 2.5L 4EAT, 2008 Impreza WRX 2.5L 5MT, 2008 Impreza Wagon 2.5L 4EAT
Joined
·
1,224 Posts
What year were those Subaru's? I wouldn't recommend that on a 2008 unless he verifies that he can do it. Unlike older generations, the newer generations have a more complicated use of the rear sensors and aren't a good fit for the extenders. Since I don't routinely do it, I don't have mad data towards that end, so maybe he can find something else out but for a 2008 I don't think this is the ticket.
Mine were a 99 and 03. I mentioned in my post to validate whether or not it would work for a 2008. As you know the older ones (with two sensors) are a different animal to the PZEV setup.

The link to the P0420 post is a good place for the OP to start reading.
 

·
Registered
1999 30th Anniversary Legacy Outback DOHC 2.5L 4EAT, 2008 Impreza WRX 2.5L 5MT, 2008 Impreza Wagon 2.5L 4EAT
Joined
·
1,224 Posts
Interesting, thanks. So do you reuse the old o2 sensor or still replace it?
For your car I would probably change the rear sensor first. Not known how this mod will affect the PZEV and newer vehicles
 

·
Registered
2000 Outback 2.5L 5 Speed, 2014 Outback Premium 2.5L CVT
Joined
·
153 Posts
Discussion Starter #16
Have you read through my thread for P0420? I know its lengthy, but it shows in several post that its not always the CAT, sometimes its a little thing. The oil consumption can create flow issues for the CAT as well as increasing the carbon that the CAT can't reburn, like an engine running too rich. The CAT is designed for operation in specific tolerances for application. http://www.subaruoutback.org/forums/66-problems-maintenance/49537-p0420-diagnosis.html
Thanks for the reply and link to your thread, I've read the first page then realized it is 132 pages! Have to wait until later for the rest.

This is why I started this thread, I'm trying to figure out if the other problems I'm having and had with this car possibly caused the cat to fail. Since I don't have a scan tool to help diagnose this I may just try the o2 sensor next time it needs an oil change and I'm under the car.

I really don't know what to do with this car, I really like it when it is running well but it has been a disappointment. I thought about trading it when Subaru had 0% financing, but what they would give me in trade made me sick, and I don't feel right selling it to a person knowing it has problems.

There is a shop about 2 hours from me in St. Louis that specializes in Subaru and I have heard good things about them, I may take it up to them sometime and just see what it would cost to get the whole car back in good running order.
 

·
On the Super Mod Squad
2002 Pair: 3.0 VDC Wag & 2.5 Limited Sedan
Joined
·
26,197 Posts
Thanks for the reply and link to your thread, I've read the first page then realized it is 132 pages! Have to wait until later for the rest.

This is why I started this thread, I'm trying to figure out if the other problems I'm having and had with this car possibly caused the cat to fail. Since I don't have a scan tool to help diagnose this I may just try the o2 sensor next time it needs an oil change and I'm under the car.

I really don't know what to do with this car, I really like it when it is running well but it has been a disappointment. I thought about trading it when Subaru had 0% financing, but what they would give me in trade made me sick, and I don't feel right selling it to a person knowing it has problems.

There is a shop about 2 hours from me in St. Louis that specializes in Subaru and I have heard good things about them, I may take it up to them sometime and just see what it would cost to get the whole car back in good running order.
if you are looking to buy a new subaru, and ditch the old one. no need to do that at the same place.

Carmax would probably give you a better price then the dealer
 

·
Registered
2000 Outback 2.5L 5 Speed, 2014 Outback Premium 2.5L CVT
Joined
·
153 Posts
Discussion Starter #18
if you are looking to buy a new subaru, and ditch the old one. no need to do that at the same place.

Carmax would probably give you a better price then the dealer
I'm honestly not looking to do that at the moment, it was just a point of frustration last winter when I looked under it and saw a huge puddle of oil. It ended up being just the oil pressure sensor, a $25 part, but before I figured out that is all that it was my wife and I were really thinking about it. We eventually decided we like being out of debt more (all but the house) and we would replace the $25 part.

I'm also just leaving my current job and starting my own business so I'm not looking to spend any more money than I need to right now, so I'd like to keep this one running. However I don't want to do major damage to the engine by continuing to drive it, another reason I started this thread.
 

·
Registered
OBW H6 VDC, Tribeca, XT6
Joined
·
12,391 Posts
. However I don't want to do major damage to the engine by continuing to drive it, another reason I started this thread.
Ignore it. People do it *all* *the* *time* for 100's of thousands of miles, it's innocuous as i said in my last reply.

Keep an eye on fluid loss, gas mileage, and other symptoms, ignore this.

As cardoc said - you're better off diagnosing than throwing parts at it.

If it has any exhaust leaks, then definitely sure those up.
If it has drivability or gas mileage issues - repair those.

Mine were a 99 and 03.
That works for pre-2004 stuff, I'm unsure of the repercussions for 2005+ but I think efficacy is far reduced if applicable at all.
 
1 - 20 of 25 Posts
Top