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Subaru Legacy/Outback "Check Engine" Light Problems

406 messages,  Last post on Mar 07, 2013 at 11:38 AM

You are in the Subaru Legacy & Outback Forum.

What is this discussion about? Subaru Legacy, Subaru Outback, Wagon

Messages Page 19 of 42

#174 of 406 Re: 2001 Subaru Outback with Check Engine Light [haljordan1] by fibber2

Jan 29, 2010 (6:20 pm)

Replying to: haljordan1 (Jan 29, 2010 5:25 pm)
The OEM Oxygen Sensor is around $100 for the front, $135 for the rear. Add in an hour or so for reading the code and scoping the sensor output. Good diagnostics include making sure that this is really the cause, and not something that is simply fingering it as the cause! Change the sensor, rescope to be sure it works, then test drive and read the codes again to be sure that it hasn't logged a new pending code that will throw a CEL two days from now.
 
Add it up, and I'd say you are north of 2 bills!

#175 of 406 CEL Catalytic Converter by frogzone

Jan 30, 2010 (11:13 am)

I have a 2002 Outback and the check engine light has been on for a couple of years now. This year, my mechanic said that it will no longer pass emissions testing and I have to resolve the issue. His code pointed to the catalytic converter, but he said that I need to have the dealer do it because he's replaced a bunch of them and the CEL comes back on. After reading the thread above, I'm reluctant to pay $1200 to replace the catalytic converter if that is not really the problem. How will I know before spending the money? And is this a common problem? Thanks.

#176 of 406 Re: CEL Catalytic Converter [frogzone] by fibber2

Jan 30, 2010 (2:53 pm)

Replying to: frogzone (Jan 30, 2010 11:13 am)
I could write a book on this subject, but don't have time to elaborate today. Basically, I personally don't like simple code readers because they tell you little, leaving you to guess what to fix. A computer scanner gives you snapshot data of the events logged at the same time surrounding the throwing of the code. Plus OBD realtime monitoring under operating conditions (plotting RPM, load, temps, throttle position, front and rear O2 sensor output voltage, etc.) provide solid data that can pinpoint the probable cause of fault. Finally, the dealer can tap directly into the O2 sensor wiring and scope the output to confirm that the wiring back to the ECM is OK. It could be an ECM mental problem, an oxygen sensor issue, an inefficient cat, or even something as simple as a temperature sensor calibration that is allowing the system to switch from open loop to closed loop too early and logging a code before the cat is fully warmed up.
 
Your local mechanic is smart. Without the proper tools, he can only begin changing things and hope for the best. You'll pay more at the dealer, but they then have to warranty their work.

#177 of 406 Re: 2001 Subaru Outback with Check Engine Light [haljordan1] by ateixeira

Jan 30, 2010 (3:00 pm)

Replying to: haljordan1 (Jan 29, 2010 5:25 pm)
All things considered both issues are resolved and you spent a lot less than I expected, so call it good.

#178 of 406 Re: CEL Catalytic Converter [fibber2] by ateixeira

Jan 30, 2010 (3:02 pm)

Replying to: fibber2 (Jan 30, 2010 2:53 pm)
Yup, they only describe a symptom.
 
If the cat is going bad, it still had to be something upstream that let unburned fuel pass, which clogged up the cat. A new cat may just clog up again eventually.

#179 of 406 Thanks fibber2 by yasu

Jan 30, 2010 (4:08 pm)

Thanks fibber 2 for your response. I look forward (hopefully before too long) to your piece that you are going to write on this subject. My 2002 has been a great snow car for me and it runs great except for that pesky CEL. I am past the point of no return financially with this car and if I could get to the bottom of it and find out what is causing this.. I would be a very happy person. Has Subaru ever ackknowledged that this is a problem? At this poiont I am not asking them to pay..just tell me what it is so I don't have to keep paying. At least on here I know that I am not alone..misery loves company..I guess. Again..many thanks for your reply.

#180 of 406 Re: CEL Catalytic Converter [frogzone] by dswiss

Jan 30, 2010 (5:59 pm)

Replying to: frogzone (Jan 30, 2010 11:13 am)
Well, frogzone, I don't want to ruin your day, but I have to tell you that I went through three new cat converters and numerous replacements of sensors, switches and even a totally new transmission at three different dealers on my Legacy. All this within the 36000mi warranty. When it hit 36000 and the CEL came on again, I sold the car. As you can tell from reading through this thread, this problem is not a maintenance issue, but a basic design flaw to which Subaru has never admitted to. I don't know if the newer models still have this issue, and I don't want to find out. I lost so much $$$ on my car that I am done with Subaru.
good luck with yours.

#181 of 406 Re: CEL Catalytic Converter [dswiss] by fibber2

Jan 30, 2010 (9:41 pm)

Replying to: dswiss (Jan 30, 2010 5:59 pm)
Just another quick visit...
 
(You are welcome, Yasu. I really need to stop promising an article. You'll just have to put up with occasional posts!)
 
I'm not convinced that Subaru has a specific problem in this regard, but it may be true that they have either a bit more delicate system, or less useful diagnostics that impact the ability to pinpoint the cause. I'm present, but less active on the Honda boards. Plenty of very similar OBDII complaints over there. Personally, I went thru hell with the evaporative emissions system on a '97 Dodge GC for 3 years before finally getting rid of the van. I understand the frustration.
 
Realize that OBDII was first introduced in 1994, but the roots of the standard (readout interface, selection of sensors to be monitored, etc.) dates back 2-3 years prior. Think for a moment about the state of computer power both under the hood, and on your desktop in 1991-1992. For me it was an 80386 PC running Win 2.0 or 3.0. Most cars still had carbs or throttle body injection. Pretty darn crude! The "P0" codes - those mandated by the EPA were locked in then. That is all that your handheld code reader tells you about!
 
Manufactures are free to add their own proprietary P1 codes, but you must have a manufacturers specific add-on to be able to view and interpret those. Only well equipped shops have the resources for that. Then there are the Transmission, Airbag, Controlling Network (much newer cars), and others that very few of us can read out. Some mfgrs have added hundreds of extra readouts. Last time I looked, Subaru was rather light in this area. The net is that this limitation may make it harder to diagnose and pin down the cause of a fault.
 
Another aspect is "what exactly is a fail"? Mfgrs must certify compliance to whatever the pollution standard was in force in that model year. OBD is then set by the mfgr to throw a code on that vehicle if the measured output by the rear oxygen sensor is 1.5x the certification limit. Honda got nailed some years back for cheating and setting it at something like 2x to cut the number of CEL complaints!
 
Do Subaru engines degrade faster, exceeding the 1.5x limit? Could something degrade the cat so that it doesn't do it's job efficiently? Could head gasket issues (internal leaks) come into play on some cars? Could sensor placement issues make them more susceptible to being dulled and not respond properly? Could the front sensor be seeing the unburnt gas, yet the required adjustment limits are outside of the ECU map to fix it, and beyond the cat design to clean up the mess? Could other things trick the system to logging a failure during warm-up (like an out of calibration temp sender I mentioned earlier), when there really is no failure?
 
Two years ago I was at a Failure Analysis conference that had an Auto Industry panel discussion, and I asked when OBDIII might be introduced given how inadequate OBDII was. They said they'd get back to me on that....

#182 of 406 Re: CEL Catalytic Converter [fibber2] by fibber2

Jan 31, 2010 (11:00 am)

Replying to: fibber2 (Jan 30, 2010 9:41 pm)
A thought came to mind as I was out driving this morning.
 
Imagine if as among their proprietary codes Toyota had included a gas pedal pressure transducer and a throttle cable rate-of-return sensor, in addition to the already mandated throttle position sensor? They would have nailed this sticking gas pedal issue 3 years ago, saving them hundreds of millions in losses so far. This could grow to a $1B issue for them (lost sales, liability, replacement costs) as the details unfold.
 
All mfgrs will come to realize that the payoff is great for better self diagnostics.

#183 of 406 CEL and oil leak by patb1227

Jan 31, 2010 (10:35 pm)

I love my outback-I have had it since 2002. 150K miles but my CEL light is coming on and going off by itself. The first time this happened I had it checked and garage informed me they didn't know why but said oxygen sensors or catalytic converter and I should take it to the dealership. How many converters are on the outback wagon LL Bean? I also have had a minor oil leak for the last two years-it appears to be minor and I have been monitoring it-love this car-It has everything I want-I did notice my mileage has dropped on long trips. I used to get up to 28 MPG now I am getting 22-23. Could this be the oxygen sensor?

Messages Page 19 of 42

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