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2011 2.5X Touring
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Discussion Starter · #1 ·
CEL had come on 3 times since mid July / 88K miles but cleared. Fuel mileage started dropping mid September, now down 2.5 MPG. CEL came on again Thursday 10 October. Dealer scanned the codes and said the front catalytic is bad and the air mass flow sensor needs to be replaced.

Bought the 2011 Forester 2.5X Limited just after Christmas 2010 and put it into service on 12/28/10. Change the oil and filter myself with 0W-20 Valvoline synthetic and FRAM PH 9688 every 7K miles. Use a K&N air filter & have cleaned it 4 times now. Cabin air filter changed every year, next one due in December.

The vehicle gets driven a lot, as you might gather. Wife puts 95 miles on it every day I'm not using it. When I use it, it gets at least 500 miles each way. Most recently was Cleveland-Toronto-Chicago-Cleveland 9/26/13-10/10/13.

30+ years driving cars with cats, and this is the first one that's ever failed on me. Very disappointed. Not even 3 years old and of course, now 16K miles past the emissions systems warranty mileage limit. Dealer wants $1,200 to fix it and the part is dealer-only. I've started a case with Subaru in an effort to get an accommodation, but don't have much hope.

This was my first Subaru and it may well be my last. Initial aggravation was having a plug change interval at 60K miles and the NGK SILZKAR7B11 plugs were dealer-only parts that the dealer didn't even have. Then after they took a week to special-order them in, they charged me $370 to replace them.

Wear parts are wear parts. But plugs required and a catalytic failing at less than 100K?!? I realize I am at the extreme high-end of mileage here, but it's all highway. Haven't even had to do the brakes yet, just tires and I got 94K miles out of the OE Yokohamas.

Does a catalytic failing this fast seem wrong to anyone else?
 

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'19 Forester LTD CVT
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60k spark plug interval is pretty high for the industry. Some intervals are as low as 20,000 and more commonly 30,000.

What it sounds like (mass airflow sensor has to be replaced) is that the MAF went bad, and started running rich. Thus MPG dropped. The rich condition caused by a bad MAF isn't good for the cats (causes premature failure). I would replace the MAF yourself (not hard if you change your oil) and have a local shop put a weld in cat instead of ordering the entire pipe from Subaru (which is the expensive part).

A denso MAF (who makes the OEM MAF I believe) costs $92+shipping from rock auto (and then google for a 5% off code that are always present). Very easy to install. I don't have my 2011 forester in front of me for reference, but I believe it is two bolts and one wiring harness to replace it.

As for the cat at a local exhaust shop it might cost you no more than $400. Might even get as low as $200.

It is a very rare failure, but statistics dictate that it has to happen to someone.
 

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2010 Forester 2.5X
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So, did you bypass the 60K plug change and do it at the mileage you are at now.. which I assume is close to 100K?
Plugs aren't dealer only and they are about $20 each, but somewhat difficult to install on the DOHC motor.
Amazon.com: NGK SILZKAR7B11 Laser Iridium Spark Plug: Automotive

I would get rid of the K&N air filter and go back to standard filter.
Try cleaning the MAF, or replace. CRC spray cleaner at auto parts store.

In California it's easier to buy a firearm than a cat. convertor.
And it would be a factory or approved part.. no aftermarket allowed.
Must be put on by a qualified tech.
I don't believe you can just weld in a new one for the front.
 

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2014 SJ XT CVT
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147 Posts
Catalytic may fail because of oil, passing through it.

Does your engine burns the oil? How much?
 

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2011 2.5X Touring
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11 Posts
Discussion Starter · #5 ·
Clarifications & update

Fuel mileage didn’t start dropping until 12 September 2013, just after tires were replaced at 94K miles with Continental Pure Contacts. Waited until now to make sure mileage change wasn’t just the tires. Have a hard time believing that only 3K miles of running rich would so severely damage the catalytic. Those things were designed back when carburetors, points and condensers ruled the under-hood roost and had to be far more fault-tolerant than that. Note also that the California warranty on the catalytic converters, ECM and related core parts is 100K miles, so a cat dying at 97K is unexpected by any measure.

On the plugs, they were finally changed 14 December 2012 @ 69K miles. Tried to get them changed in September 2012 when the car hit 60K miles at my local mechanic, but the plugs were not available through any of the wholesalers in Ohio. At that time, they were also not available through Amazon or anyone else online. The NGK NA Website referred the user to Subaru, too. As stated in the original post, even the dealer took a week to get them in. Since the car was only 19 months old with a new engine design and from a low volume manufacturer, that was not entirely surprising, just annoying and grossly over-priced.

Have to disagree that a plug change interval of 60K miles is at the upper range or that 20K to 30K intervals are common in current production vehicles. Our 2008 Mazda MX-5 has an interval of 75K miles, while our 2000 Workhorse motorhome chassis with the 7.4L GM big-block has an interval of 100K miles. Both of those are older and much higher performance engines (albeit in different ways) than the 2.5 in the Subaru. Even our 99 Audi A4 1.8T Avant had an interval of 100K. The days of loosely regulated combustion killing plugs and necessitating short change intervals are long gone. The only reason I can see for the NGK plugs requiring such a low mileage change-out is that they have almost no electrode material. Which is odd considering how expensive they are.

Oil consumption is within the “acceptable” range per the owner’s manual; i.e. 1 US quart or less in 5K miles. Actual use is .75 US quart over the 7K mile change interval I use (500 miles less than recommended). I don’t really consider that entirely acceptable. I haven’t had a modern vehicle measurably use oil within the change interval in decades. That includes a 79 Ford (Mercury) Capri with the 2.8 V6, an 83 Saab Turbo, several Ford Super Duty Diesel pick-ups and even an 85 Chevy P30 motorhome chassis with a carbureted 454 and 100K miles on the clock.

Now for the update. Subaru agreed that the catalytic shouldn’t have failed so fast and granted a $500 adjustment against the replacement cost. They did so in less than 24 hours from the time I called, which says something about how unusual a catalytic failure at 97K miles should be. That is an impressive act of customer service and speaks highly of their desire to satisfy a customer with a very demanding application. My faith in the brand has accordingly been restored.
 

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2000 Impreza, 2003 Bugeye Sport, 2010 Base, 2014 Base, 2015 Premium, 2017 Limited, 2020 Touring
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Good to hear SOA came through for you on the cat converter.
 

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2015 Highlander AWD XLE 6AT
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Note the the California (PZEV) emissions warranty is 150K miles, and also includes a different cat, and, IIRC, added $300 to the car's price.

Good news from Subaru about helping out with the repair!

Regards,
Jim / crewzer
 

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2014 Forester xt prem Cvt
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161 Posts
the K&N will increase flow and reduce drag on the engine. so you would run about 5% rich. Id put the stock filter back in if you didn't get a retune with the K&N. difference in HP from stock filter to K&N is about 5HP, thats not worth a busted cat due to rich gasses getting dumped into the cat, which WILL destroy your cat. I also agree with all the above comments
 

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2011 2.5X Touring
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11 Posts
Discussion Starter · #9 ·
MF sensor and K&N filter

Mass flow sensor is at the top of the snorkel running to the intake manifold a few inches downstream of the filter housing. Piece of cake to clean and change - 2 Phillips head screws and one modular plug. Thanks for the tip!

Existing unit appears clean and whole; not sure if it can be bench tested with a standard multimeter. If anyone knows what kind of voltage, current or resistance it should have and the test points that should be used, please clue me in. In the meantime, I'll just add cleaning it to the annual maintenance routine.

Don't understand what difference an air filter could possibly make to air/fuel mixture in this case. Isn't the whole idea of the MF sensor, FI and ECU system to match fuel delivery to throttle demand and air mass flow? A less restrictive air filter only means that the throttle doesn't have to open as far to achieve the same specific output for a given air/fuel ratio.

Have to conclude my catalytic was just not up to snuff. Ohio (and most other states) emission systems warranty is 8 years / 80K miles, CA (plus I think 8 other states) extended emissions systems warranty is 8 years / 100K miles and CA PZEV (plus other states accepting the CA PZEV designation) extended emissions systems warranty as noted above is 15 years / 150K miles. Mine did not come with the PZEV appliqué, but I was offered one at no charge as a courtesy follow-up by SOA about a month after I bought the car. That leads me to believe that all 2011-2013 Foresters are 50 state vehicles. It also explains why SOA came through with an accommodation so fast.

Regardless, the car goes in for the new parts 24 October, so should be good to go. Thanks for all the input!
 

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1999 Forester 5MT
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the K&N will increase flow and reduce drag on the engine. so you would run about 5% rich. Id put the stock filter back in if you didn't get a retune with the K&N. difference in HP from stock filter to K&N is about 5HP, thats not worth a busted cat due to rich gasses getting dumped into the cat, which WILL destroy your cat. I also agree with all the above comments
It will not cause a rich condition. If anything, the extra flow would cause the engine to go slightly lean.

Though, there are other reasons not to use a K&N. The oil likes to come off the filter and gum up MAF sensors. Cleaning it would probably restore the one you have. If you really want a reusable filter, get one that has no oil involved. Something like the AEM DryFlow series.
 

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2011 2.5X Touring
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11 Posts
Discussion Starter · #11 ·
Update

Got the cat & sensor changed out last week @ 96847 miles. Turns out the sensor needing replacement wasn't the air intake mass flow sensor, it was the air/fuel sensor AKA oxygen sensor on the exhaust manifold, part number 22641AA610 SEN AY A/F RATIO ($219.99 list).

Car seems to run normally and fuel mileage as calculated by the on-board computer appears to be returning to the expected 26 to 27 MPG. Should know for sure by the end of this week.

Dealer experience was not ideal. They are the closest one to where I live, but are still a 100 mile round trip. Key-dropped the car Wednesday night for the service scheduled the prior Thursday (10/17/13), so they had a full week to get the parts. Got a call about noon Thursday (10/24/13) - they forgot to order the required exhaust gaskets and O2 sensor. Had to wait another day for them to come in, then got a robocall saying they were sorry I'd missed my appointment. Had to call them at the end of the day Friday (10/25/13) to find out if the car was done. It was. Finally picked up the car on Saturday morning (10/26/13).

I'm pleased SOA made the accommodation because the cat simply shouldn't have failed this fast. That was a smart act of customer service. Jury is still out on the car itself - have to see what else crops up in the next 2 years. The dealer, meh.
 

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2015 Highlander AWD XLE 6AT
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That leads me to believe that all 2011-2013 Foresters are 50 state vehicles.
Our 2012 Forester is a PZEV model, but it was an extra-cost option for that model year in Virginia. IOW, I could have bought a regular ol' non-PZEV model.

My understanding from cars101.com is that PZEV became standard for all states on the MY2013 Forester non-turbo effective with April 2012 production.

HTH,
Jim / crewzer
 
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