Check engine light and Traction light on.
 

My 2014 Subaru Brz limited has only 1 mod and it's a drop in k&n air filter. After installing the filter I drove the car for a week without any problems and then I had my check engine light and traction light on on my way back to work. I got an OBD scanner and got the following codes:
P0171 - System too lean Bank 1
P117B
P1170

I took out the filter and reassembled it into the air box yesterday and also cleaned the maf sensor with CRC maf sensor cleaning liquid. Disconnected the battery and reset the ECU. Took it for a test drive and no problems.

Today when I started the car and before going a mile the check engine light and traction light is back on. Traction light goes away after some time and
comes back again. Check engine light remains on and stays on.

What do I do to fix this? I have no idea what's happening as I'm a noob to the car scene. If anybody can advise that would be great. I live in the waterloo region in canada and would love to take the car to a good mechanic in the region if anybody can suggest one for me please.

Try putting the stock air filter back in and see? Did you knock something loose? Any images of the engine bay?


All seem like fuel injector codes.

Hello ser1alchill3r and welcome to our forum - :clap:

It appears that you have done the easy things. Considering your limited knowledge of that car, I would recommend that you take it into a shop and have them fix it. Meanwhile you may wish to look up those codes on line and follow their leads to look for a bad connection that would effect an injector.

I hope you get er fixed soon.

Thanks @humfrz.

I will be getting a new stock air filter tomorrow and will reset the ecu again with stock air filter and see what happens.

How many k? How long have you had the car?

113000 kms. I bought the car recently when it was at 100000.

OK, also make sure you have the MAF plugged in proper.

Ignition coil, most likely cyl #1

Hello, why do you think it's the coil pack? OP seems to have his CEL on right after changing his air filter, so it must mean that his air filter is the problem, no? I'm not trying to be rude, I am genuinely curious because I have the same problem :lol::lol:.

Might just be a coincidence. Coil packs can be a common issue on the platform, especially for the early models (MY13 and MY14) before the coil pack was revised

If the symptoms are known, it's worth checking.

At 100k km, may be spark plugs based on service internal. Though if the car was always NA, spark plugs usually are pretty clean.

I have no idea what's going on. So I'm going to take it to a subie mechanic tomorrow. Hopefully it's nothing bad. I'll keep you guys posted. Thanks a lot for pitching in with your honest opinions.

A very quick search on those codes came up with the below thread among others. Sounds like it is an air leak somewhere. Did you undo any hose clamps when changing the filter?

There is also someone who's battery died and the low voltages were tripping codes like that. More likely an air leak in your intake tho.

https://www.ft86club.com/forums/show....php?p=2128963

Check engine light and Traction light on.
 

The behavior of warning lights and obdii codes. Yes I agree it’s not obvious and there are certainly other possibilities ( for a bank to run lean, can be too much air or too little fuel in normal thinking, I think it had to do with short/long fuel trim and in a particular situation that our car seem to get into. The problem completely went away after replace cyl1 coil, in my particular case. Ymmv

Ps I too checked for leaks, fuel supply etc, until noticed a thread where cyl1 coil often fail on these cars prob due proximity to exhaust header.

I booked an appointment on Thursday with the mechanic. I dont think it's the coul pack cos I dont have a single misfire as per the obd scanner. However my LTFt and STFT are off the charts.

How did it go with the mechanic? I'm currently in the same situation with the P0171 code. I'm planning to try the ignition coil on bank 1 as Milanjess suggest.

I wasn't able to take it to the mechanic today. But will be doing it tomorrow. I think thats the case: coil pack on bank 1 or vacuum leak or the fuel injector. I dont know for sure. I tried going back to the stock air filter and didnt make a difference. Will update you tomorrow.

FIXED
 

Hey guys. Got her fixed.

Ultimately it was a vacuum leak in the intake at a point past the MAF sensor. The belt was rubbing against this guy. I don't know what this part is called but the mechanic said it was there to baffle intake sound and to fix it: he deleted the part and closed the opening with a cap. So that thing is not in my car anymore. He also said that I could spend about 85 CAD and get it from the dealer if i want to. But I'm not gonna bother about it cos I don't mind extra intake sound unless one of you suggests it has some important function that I'm not aware of.

Huge Thanks to all. This forum and the people in it are absolutely awesome. Thanks for the suggestions and support. I hope this thread comes of use to people in the future.
:thanks:

The screenshot was taken from here:
https://www.youtube.com/watch?v=770lUIa2cZQ

Thanks for the update! Glad it was an easy fix for you. That intake baffle part seem to be a common issue for this platform. I believe there was another tread about it this forum.

I had no idea about this issue. Anyways it's fixed and done. LTFT and STFT are back in range. And I dropped the k&n filter back in so back to better throttle response and smoother rev matching. XD

I am glad the problem was fixed. But, all this trouble was for modifications without any gain. K&N filter (or any other intake modification) does not make any difference other than changing the sound. K&N filter can cause additional trouble by blowing oil to MAF sensor if you oil the filter just a bit too much when you clean it. I also wasted enough money and time for unnecessary modifications.

My personal opinion on K&N drop in filter is that it does a great deal of improvement to the throttle response. Makes blipping n matching a lot easier and smoother for me. So I would never say K&N drop in filter mod is unnecessary.

However, I agree to your comment on the filter blowing oil to MAF sensor if oiled a bit too much when you clean it. I dont mind cleaning the MAF sensor after putting some miles on the car after u clean the filter. Its easy to do that. This is what I think.

XD