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Old 01-21-2019, 08:50 PM   #1
STiBro
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Member#: 39546
Join Date: Jul 2003
Location: Fountain, CO
Vehicle:
2010 WRX Sedan
Blue

Default Newbie With Freshly Bot 2010 WRX Needs Help - P0171 & P0456 CEL

I did own a couple '04 STis back in '04 and '05 (1st one bought new), but I never did any work on them myself, so while somewhat car-savvy (have owned several Buick Grand Nationals), I'm not too familiar with these cars.

I'm excited to have *just* picked up (3 days ago) a 2010 WRX Premium with 150K miles, well cared for, with a few bolts-ons. From what I was told (and can see), it's got:

- CAI
- CNT downpipe
- Magnaflow exhaust
- BOV
- BC racing coilovers

As I mentioned, I've had it 3 days. All's been good after about 8-10 short (<10 mi.) drives, until today. Well, had a 30+ min. drive home the night I bought it without problems. Today, after driving about 5 miles, the check engine, traction control and cruise light (blinking) came on.


I have an OBDII reader (just like most auto parts stores have); checked and got P0171 and P0456. P0171 code was listed 3X, "pending", something else and "permanent". The P0456 code came with the statement like "very small leak". I've done quite a few searches on this forum and have got some tips, and now understand that 171 means it's running lean (or thinks it is, from what I gather), and the 456 is a leak in the evap system (AC?).

So I reset the codes and for a few minutes, it ran poorly, namely stalling at idle. My thought was that it had to relearn, and it appeared to, eventually no longer stalling. All was good until the ride back home (first drive was 25 minutes). Same dash lights, same CELs.

I'm in Colorado at about 5,700 ft elevation. When I first moved to CO from CA 13 years ago, my STi kept getting a lean CEL (forget the exact code #), which was determined to be caused by the higher elevation. I had it tuned and fixed that way (nice, because also got ~25 more hp).

The seller told me he bought it to flip and it came from Texas. I wouldn't want to bet whether the seller reset the codes for selling or that he just didn't own it long enough for them to trip.

I guess my first question is: Wouldn't the lack of cats on the DP/exhaust trip induce CELs? I'm assuming there are still O2 sensor/s, yes? I haven't looked closely enough yet.

I also read that dirty MAFs are a somewhat common culprit, but...couldn't find the MAF at first look. It is under the IC? I'd like to post a photo of the car (to see if anyone recognizes it) and of the engine bay, but I don't see any option to attach photos.

And to prove I'm a newbie, I don't even know where the ECU is located to see whether it has an AccessPort (assuming it would be near the ECU).

Pardon the long post, but any help is greatly appreciated.
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Old 01-24-2019, 12:41 PM   #2
haishouf
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Member#: 469046
Join Date: Jun 2017
Location: McAllen, TX
Vehicle:
2009 WRX Hatchback
White/Black(Stormtroopah)

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Well first off, you would definitely know if you had an access port. They plug right into the OBD sensor. At least the recent V3 and V2 accessports do. Your MAF sensor will be on your CAI, right after the filter and normally right before the turbo inlet. Itíll have a plug leading from it to the main wiring harness. Thereís tons of How Toís on cleaning them on YouTube so thatíll rule out that possibility. As for the car running improperly, I canít say too much other than I live in Texas and my 09 WRX is tuned for sea level. My tuner has told me that drastic air changes can affect the car but mainly with much more modified engines (which mine has a fair bit done to it). Wish I could help more, good luck!
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Old 01-24-2019, 02:08 PM   #3
Turpid Porpoise
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Join Date: Oct 2017
Chapter/Region: MAIC
Location: Virginia
Vehicle:
2008 Impreza WRX STi
Silver

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P0171 - You have a CAI, catless DP and BOV with no Accessport. These are major no nos for modernish Subies

https://forums.nasioc.com/forums/sho...d.php?t=475620

P0456 - https://forums.nasioc.com/forums/sho....php?t=2779400
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Old 01-24-2019, 05:34 PM   #4
STiBro
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Join Date: Jul 2003
Location: Fountain, CO
Vehicle:
2010 WRX Sedan
Blue

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Thank you both for your input. Nothing connected the OBD connector, so that answers that.

Right at the CAI was the first place I looked for the MAF. I'll look again. It was probably right in front of my eyeballs. I saw something electrical connected to the end of the CAI tube, nearest the filter. Figured it was the air temp sensor.

Anyway, there's a dyno tuning shop (Under Pressure Performance) in town that I think I'll just take it to after I buy and install a GrimmSpeed TMIC. They can tune it for the elevation, CAI and everything else to get it running optimally.

I'll find and clean the MAF though.

Maybe newbies have to have a minimum # of posts before the website allows attachments? Still see no option to attach photos.

Other than the CEL issues, it could use new front rotors (warped). I'll pick up some drilled slotted rockauto rotors. The rear diff is also leaking, I believe at the axle seal. I might just have the shop inspect and have a new seal put in. Either that or just buy a used one and R&R it myself. I've done lots of wrench turning over the years, but I'm getting old and mostly lazy!

It also leaks about a 2" spot of oil after a good drive. Any common areas of leakage on these motors that I should look at first?
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Old 01-24-2019, 05:43 PM   #5
Turpid Porpoise
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Member#: 476573
Join Date: Oct 2017
Chapter/Region: MAIC
Location: Virginia
Vehicle:
2008 Impreza WRX STi
Silver

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You have to host the images on a hosting site like photobucket, imgur or imgbb and then use the forum codes generated to post them on here.

Most common oil leaks are the valve cover seals, turbo oil drain hose and power steering lines. Park over a clean sheet of cardboard, see where it drips and try to see what is directly over that spot. Try to trace the oil up the motor to the source and post pics so we can help you out.
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Old 01-25-2019, 11:20 PM   #6
STiBro
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Member#: 39546
Join Date: Jul 2003
Location: Fountain, CO
Vehicle:
2010 WRX Sedan
Blue

Default

Ordered the ol' (new, actually) GrimmSpeed TMIC today. Not cheap, but...had to be done. Stock IC is entirely too puny.

Once installed, a tune will be perpetrated.

Let's see if this works (photo): http://www.stellarspas.com/images/WRX1_000.jpg
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