SES light :(
 

So im at about 50K on my 09' base and the SEL light came on...
I figured it was a fluke or just a gas cap code as I have heared its pretty common or also since I had no choice to put about 20 bucks in gas at some random gas station the night before so I cleared the codes the following morning...

About 2 days later driving to work in the morning the SES light came on again and throwing the same codes. Keep in mind I had already filled up with 91 from a reputable gas station. No obvious change in the driving even though I did not get on it at all I did however have to merge onto a highway to get to and from work but no issues, hesitation (besides for the normal throttle delay). But I did feel the throttle a little jerky when it was about 90 F outside driving from a stop, but only that specific occasion.

Codes were: P0157-159 if I recall correctly and one had a dP... im guessing its a duplicate?

So before I take it to the dealer I figured I would see what all of you had to say, maybe point me in a direction to where I could fix this myself. Since my dealer is a little shady... Example: I experienced no pressure, pedal to the ploor on my clutch, didnt come back up so they blamed it on the releaf spring behind the clutch pedal and wanted to charge 125 for it plus 400 for labor... WTF. I bled the lines and put fresh fluid in and vuella good as new!

I just dont want to throw random parts at it and hope I fix it vers getting it fixed! since I have a baby on the way im saving all my pennies and being more spend cautious than I usually am.

Thank you for all or any input.

BTW I have K&N drop ins which I have had on for quite some time now, but other than that it is stock.

P0157 02 Sensor Circuit Low Voltage (Bank 2 Sensor 2)
OBD-II Trouble Code: P0159 Oxygen Sensor Circuit Slow Response (Bank2, Sensor2)
If that's really the only thing you've ever done to the car (swap air filters for K&N): have you ever re-oiled them? Was it recent? If you over-oiled them, they can put a light coating of oil on the MAF sensors in your intake tubes.

That, or just dirty MAF sensors in general, can lead to P0159 pretty easily. P0157 is related but different, sounds more likely to be an actual O2 problem, but you never know with these things.

I'd run through all the common, easy stuff first that's remotely related:

(1) Clean your MAF sensors. They're easy to remove and replace, and you can buy MAF cleaner spray at the auto parts store. Be sure not to touch the sensors to anything, including your fingers. Just spray them down with the aerosol can from all angles once you remove them from the car.

(2) Check the whole intake tract for leaks on both sides of the engine. Look at the fittings between various intakes tubes, PCV tubes, throttle bodies, etc. Something may have come loose.

(3) Get under the car and check out the upper portion of the exhaust system, specifically around the catalytic converters. Check for loose bolts, blown gaskets, or leaks at any of the connections. Check the wiring harnesses for the 4x O2 sensors (one before and one after the catalyst on each side of the car) as well as the sensors themselves for damage (something you ran over could have hit them).

The issue with your clutch pedal is probably the clutch slave cylinder. Your dealer is out of their mind(s).

Agreed... the oil on my Mazda's K&N constantly fouls up the MAF sensor.

:icon18:Thanks for the input.... thats why I went ahead and flushed the lines as I was beating the shat out of my car the day before with some buddies and figured I boiled the fluid... The problem does come back from time to time so I plan to replace that after this issue.
Just FYI I dont take my car there anymore :tiphat:

I checked for cracks and leaks but nothin:/ however I will clean the MAFS off as that might be a good idea since I never cleaned them although I figure if the were dirty the code would come back pretty much right after I cleared the code and started the vehicle again and went for a drive but it wont hurt to try it.

As for running something over... OOOPs :shakes head: I forgot to mention im also lowered on swift springs and the light actually came on when I was comming off the highway... did sound odd so that might be the issue. I just havent had time to get under the car and look because of my busy work/home schedule:/

Thanks for the input guys, I will take a look later tonight and try to update with what I find.

Yeah if you think you may have run over something, especially check the wiring and sensors for the rearmost pair of O2 sensors (behind the cats). They're pretty exposed, I'm not fond of the design there.

As far as the MAFs go, when they're dirty/oiled it can take a while to throw something like P0157. What triggers the code is that it's trying to use the MAF input to verify the response curve of the rear O2 sensor, and after a while of driving it ends up eventually blaming the rear O2 sensor's response curve when the MAF is actually the one at fault more commonly (assuming no damage under there).

Yea I honestly dont think I snagged anything while driving even tho it sounded like I ran over a flattened bird cage but I took a look at lunch to see if I could see something without lifting the car but NO DICE... cars to efin' low so that will have to wait...

As for the dirty/oiled MAF, about how long do you think it would take until it started blaming the o2? you think 5k miles long or more like a couple hundred before it started blaming the o2?

Im realllllly hoping it is the MAF... Ill buy some MAF cleaner today even if I find out I snagged something because the more I think about it I remember them drop in were pretty oiled... or its my imagination because thats what I want it to be! lol:icon14:

No idea really, all depends on how quick the oil/dirt layer builds up, and how much it ends up affecting the sensor.

Figured that much but hoping I was going to get a magic answer lmao!

So I took a quick peak under the car and this is what I found... Ez fix now.
Thanks for all the input guys!


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I am here: http://maps.google.com/maps?ll=36.696062,-121.657040

Wow how'd that happen?

I have been getting random codes too. Something different everytime. The first time it popped up C15XX, then I got the P0159 and now it comes and goes when it pleases. Funny it only started after a really hard storm I was forced to drive home in. Im gonna check my 02 sensors to see if thats the culprit as well. Excellent thread, very helpful. Those damn 02 sensors are freaking expense.

The front O2's are the super expensive ones. They're accurate widebands that are used for realtime A:F mixing. The rears (what he damaged) should be less, they're the slow-*** emissions only ones.

EDIT: Courtesyparts.com lists the rears at $151.98 each, and the fronts at $338.69 each.

Im pretty sure it happened over a period of time... I know I have LIGHTLY bottomed out a couple times at my apartment complex. The are super big speed bumbs :icon14:

So my plan is to solder and heat shrink these before I purchase a new o2 sensor. After I will check the voltage and parameters just to make sure they are where they should be... if not Im gonna break the piggy bank open and buy a new one setting me back on what my next mod was :mad: