damn... p0170

[A4speed]

so i thought i found a gas station a few days ago with 100 octane unleaded gas bc it had a little unleaded sticker on the gas pump. i got the this code today and so i went back to the gas station and they said it was leaded, that they use to have regular 87 unleaded in their...

so with the p0170: fuel trim malfuntion (bank 1) code im assuming i fried that first 02 sensor and just wanted to confirm it with u guys...:mad:

weird thing is my car runs completely fine, boosts fine, idles fine. can't feel anything wrong...

[Cincy]

Have you tried clearing it and see if it comes back? If you still have some of the leaded gas in there, i would try to delute it to try to save the other o2 and cat if you have one.

[A4speed]

yeah, its back 91 unleaded... i cleared it and it hasn't came back on yet but i have a feeling it will.

[ImTheDevil]

Hopefully not. With only doing this on one tank of gas, and diluting down the remains of that tank, you may end up OK. Seems a little extreme that it'd kill an O2 sensor with one tank. I'm sure there's a chance it can, but hopefully that's a slim chance.

[A4speed]

^ i hope so to, i only put 4 gallons of it in, i didn't fill her up or anything.

[ImTheDevil]

You're probably going to be OK. I doubt it'll kill it that fast. If anything it may wear out more quickly than normal, but it's probably fine for awhile still.

[A4speed]

so after about 4 days, the CEL came back on with the same code.

im talking to a guy parting out his 01 a4, would it be ok to buy a used good o2 sensor off this other car or is this a part where u just wanna buy it new?

[Cincy]

If they are working, thats fine, they will just die sooner.

[A4speed]

ok cool, thanks! we need to get some more a4 guys on here, im sick of making all the threads in this section! :)

[auditech79]

Just remember most O2 sensors only have a running life of about 100k, so if the one you are buying has close or more than that mileage on it, you're just pissing in the wind.

[Cincy]

Now he knows how long they last with leaded gas :lol:

[A4speed]

^ lol

actually i cleared the code again and it hasn't came on yet, im wondering if im gonna luck out since i haven't bought the dudes o2 yet.

[Tweaked]

p0170 is not an O2 sensor code.

It simply states you have a fuel trim malfunction for bank 1 (your only bank). It's a generic code and is often accompanied by P017x, something more specific for fuel trims.

Read the fuel trims. If they are lean or rich, it will help you pinpoint the issue. The reason why the MIL turns off is becuase you reset the fuel trims when you erase the DTC.

Most common causes? Vacuum leak or MAF.


EDIT: could have something to do with your mods as well.

[A4speed]

i know 100% that i fried that front o2 sensor.

[Tweaked]

i know 100% that i fried that front o2 sensor.

How so? You'd likely have a code for it specifically, something saying the O2 is bad, ageing, or generic O2 sensor code.

Leaded gas destroys the cat, not the O2 sensor.

[A4speed]

leaded gas destroys o2 sensors too, ive already replaced the o2 and no more codes.

[A4speed]

well, apparently i am wrong actually. its been 2-3 weeks now and the code just came back on after replacing that o2 sensor, so pissed. i put a new one in too, i didn't end up using the used one. So looks like Tweaked is right.

so now i have to start looking for what else it can be. im actually a little worried that its my new turbo, but the code should have came on a couple months ago if it was so. when i took off the dual exhaust the first guy just cut off the pipe on 1 side and plugged the hole. i noticed turbulence type noise driving it home so i looked under my car and saw what he did. so the next day i go back and make them cut off the y-pipe completly and weld a new 2.5" pipe in there. the sound stayed? they said it could be my old exhaust tip thats doing it?

the sound is like the dentist drill noise of a bad turbo, and is only there at full throttle in higher rpms. and with this code on im wondering if it is so. any input on what i should do would be great!

[auditech79]

16554
P0170
Fuel Trim,Bank1 Malfunction

This is why i should double check codes you guys give, this is a fuel trim related concern and not an O2 sensor specific, so yes tweaked would be right.
Im lost as to what you're saying with your exhaust, are you saying that he did custom work before the O2 sensor? Like making you a custom testpipe? If you have air escaping from the exhaust before the O2 sensor it will cause that code. But its most likely a MAF like tweaked said, tuning, or a leak of some sort.

[Tweaked]

Interesting...

Have you begun looking for vacuum leaks? Also, why are you running a 5 bar FPR with a K04 Hammer file? GIAC is usually tuned for 3 bar FPR. Is it adjustable?

[A4speed]

I was told by Streamline (GIAC dealer) that the pc-16 file required 3 bar fpr with bigger injectors while the Hammer just required an upgraded 5 bar fpr.

auditech: i had my k04 put in mid december. when i got into my car wreck in january i did not put a new rieger kit back on my car, just put stock pieces back on instead. since i had a y-pipe with dual exhaust i had one of the sides removed so it would just go out that one slot on the left side. but the guy just kind of hacked 1 side of it and plugged it up. it made a weird turbulance noise (whining sound like a bad turbo) so i took it back and they cut the y-pipe completely off and welded a new piece of pipe in there but the noise continues to exist. so, nothing to do with the o2 sensors or cat, i was just worried it might actually be a bad turbo instead of something to do with the exhaust and thought it could somehow throw that code. hope that makes more sense.

[Tweaked]

I was told by Streamline (GIAC dealer) that the pc-16 file required 3 bar fpr with bigger injectors while the Hammer just required an upgraded 5 bar fpr.

It seems big for just a K04, but it's totally dependent on what the manufacturer tunes for. The dealer knows the requirements for the setup, so I would trust them.


auditech: i had my k04 put in mid december. when i got into my car wreck in january i did not put a new rieger kit back on my car, just put stock pieces back on instead. since i had a y-pipe with dual exhaust i had one of the sides removed so it would just go out that one slot on the left side. but the guy just kind of hacked 1 side of it and plugged it up. it made a weird turbulance noise (whining sound like a bad turbo) so i took it back and they cut the y-pipe completely off and welded a new piece of pipe in there but the noise continues to exist. so, nothing to do with the o2 sensors or cat, i was just worried it might actually be a bad turbo instead of something to do with the exhaust and thought it could somehow throw that code. hope that makes more sense.

Was the turbo used? I can't imagine how bad the back pressure must have been with half of the Y just plugged up! Pull the cat/test-pipe off and check for shaft play.

On the other hand, I've never seen a functioning turbo (despite noise) throw a P0170 code. You have a completely modified intake box; begin checking all the hose connections, especially around the MAF. Additionally, have you done some of the basics like check for boost leaks? Rule out anything obvious or mechanical, then you can start investigating a possible tuning issue.

Do you have a VAGcom? What are your fuel trims like? What is your primary O2 sensor reading?

[A4speed]

i wish i had vagcom. life would be so much easier then... :D

i have not starting checking for boost leaks or replacing the maf yet. to be honest its been freezing here the last few days and without a garage i haven't been able to find a warm spot. i will get on it as soon as theres a descent day and give u guys an update.

the turbo is new from gpopshop (although rebuilt) and had 0 shaft play when i put it in.

[Tweaked]

i wish i had vagcom. life would be so much easier then... :D

i have not starting checking for boost leaks or replacing the maf yet. to be honest its been freezing here the last few days and without a garage i haven't been able to find a warm spot. i will get on it as soon as theres a descent day and give u guys an update.

the turbo is new from gpopshop (although rebuilt) and had 0 shaft play when i put it in.

You can still read your O2 sensor with just a DVOM and determine if the car is running rich or lean just by reading it's oscillating voltage (a scope is best, a good DVOM will suffice). It will give you an idea of where to start, at least.

[auditech79]

You really should invest in a vagcom, standard code readers like the actron scanner that you can get at autozone will only give you a code number, you can actually get confused on what code you are looking at and may even diagnose the wrong thing...
The vag com will usually tell you what the code is exactly and it has a self diagnostics function that will help you trouble shoot, just like the dealers VAS5052. It really is worth its weight in gold. You could measure everything with a dvom but if you don't know what your looking at or how the O2 sensors work, i wouldn't try doing it. Just buy the vag com software.
As for your problems, it does sound like this may have to do with your aftermarket parts/modifications. In which case we would need specific data blocks like stored fuel trims, MAF sensor data, throttle position, O2 sensor data etc. This will make it easier for us to narrow down the problem.

[Tweaked]

You really should invest in a vagcom... It really is worth its weight in gold.

Agreed. I'd own one, but I have an over-priced macbook... which can't run many programs I need, like VAGcom software, PhatNoise software, ActiveX controls for websites I need to visit. I hate windows because it's incredibly prone to viruses, but I need it. Dang Mac OSX.

But that's why I use a DVOM. A lot.

[A4speed]

could i read those blocks with unisettings? or would the only thing be vagcom?

[CCA4]

Agreed. I'd own one, but I have an over-priced macbook... which can't run many programs I need, like VAGcom software, PhatNoise software, ActiveX controls for websites I need to visit. I hate windows because it's incredibly prone to viruses, but I need it. Dang Mac OSX.

But that's why I use a DVOM. A lot.

Don't mean to get off topic, but you should try downloading FireFox or Opera to fix that ActiveX problem. Safari sucks wang other than the fact that no one writes viruses for it because no one cares about it enough to bother lol.

Back on topic, i agree that VAG com is extremely useful and worth the money. I don't know how to use many of the advanced features yet, but i'm learning :rolleyes:

[auditech79]

could i read those blocks with unisettings? or would the only thing be vagcom?

Only vag com

[Tweaked]

Don't mean to get off topic, but you should try downloading FireFox or Opera to fix that ActiveX problem. Safari sucks wang other than the fact that no one writes viruses for it because no one cares about it enough to bother lol.


Yes. Safari sucks, I know. FireFox sucks too. I've never used Opera before. I tried using FireFox, but the drivers are still for Windows only (at least they were when I tried a few months ago), even if I run it in Rosetta mode or whatever.

But still, even if ActiveX suddenly works, I still can't use anything I need without Windows. It's an intel-based mac, but adding Parallels, Windows, and Anti-Virus software, as well as VAGcom and PhatNoise DMM, is kinda expensive.

But anyway. Any update on the car?

[A4speed]

finally got under the car a couple days ago and their is a plastic 90 degree pipe on the return line from the DV that has a crack in it. So I ordered a new one today. The funny thing is my CEL went off today as well. it must just be a really small crack causing it to go on and off. but i can def. feel and hear the leak.

the part will be in moday so ill fix it then if its a decent day.

[A4speed]

haha, the code came right back on today, dang car... ill fix that leak when the part comes in!

[A4speed]

ok, so with the free version of vagcom and my ebay cable, i got 2 engine codes.

16804 - Catalyst System: Bank 1: Efficiency Below Threshold
17584 - Shareware Version - To decode all DTC's P1176 - 35 - 00 Please register/activate.

because of the version i have (409.1), i guess it won't tell me what the second code is. my guess is it is the fuel trim issue because i have not fixed that small boost leak? if it is the fuel trim issue, do u think that would fix the cat code after i fix the boost leak or do you think running the leaded 100 octane screwed the cat up?

[auditech79]

17584
P1176
O2 Correction Behind Catalyst,B1 Limit Attained
Im not sure what this code stands for, but it has nothing to do with fuel because its stating its "behind" the cat, so post cat.
I do know that the first code is saying your cat is toast. Are you running a testpipe, or stock cat? Leaded gas can mess up O2 sensors and cat conveters i suppose.

[A4speed]

its a hfc from techtonics, damn! looks like ill have to buy a new one eventually. its so weird, the check engine light has been going on and off randomly. i put in a new front o2 sensor, do u think the back one is messed up because because the cat itself is fried?

[auditech79]

Nah, i wouldn't worry about the post O2 sensor just yet, the code says the limit is attained, i don't know whether that means its good or not, but its more likely the cat is bad. So those are the only codes you are getting?

[A4speed]

yep, thats all the free version of vagcom gave me anyway. i wonder why the shop streamline here in salt lake said i had a fuel trim issue as well as the cat. i wonder if they were trying to rip me off?

[auditech79]

The "free" version of the vag com pretty much does everything, so if thats all it says, then thats it.
And..........duh.........

[A4speed]

well, good thing the part was only $12. so do u think the leaded fuel made it so the cat is almost fried but barely hanging in their since the CEL keeps turning on and off. seems like it comes on when its warmer and off when its colder, i could be crazy though...

[auditech79]

Usually the CEL will stay lit with a really bad cat (or a testpipe) but i would think the leaded gas isn't what did in the cat per se, cats only last about 100k, so old age would be the main factor.

[A4speed]

the hfc ive had on for 40k miles now, so not to old yet. i just dont get it, lol :)

[auditech79]

What, does that mean high flow cat? Well, i don't know if those would read correctly in the first place.

[A4speed]

yeah, its a high flow cat from techtonics, they make good shiz too, had no problems til i put the leaded fuel in...

[auditech79]

Well, regardless the CEL doesn't lie. The stock eberspacher cats flow with the best of them so i would just either buy a test pipe or a stock cat. There is no need (and most likely no gain) from a techtronics cat.

[A4speed]

how much are stock cats?

[auditech79]

For a 1.8T, i think $600 last time i checked.

[Tweaked]

yeah, its a high flow cat from techtonics, they make good shiz too, had no problems til i put the leaded fuel in...

I thought you replaced the cat after you killed it with leaded fuel?

Have you replaced the leaky DV pipe?

And stock cats have gone up... $750 + core IIRC. Check out Labree, they sell a good piece, 3" in, 2.5" out, perfect for your K04. Going back to a stock cat will disappoint you and cost a buttload.

If you still get a cat efficiency code, get a non-fouler. Some guys have had to run them with HFCs.

[A4speed]

^ nope, i didn't even know their was a code for the cat until i got the free version of vagcom a few days ago. their is no fuel trim code so i don't even know if i need to replace that 90 degree pipe on the dv return line, the shop might have tried to get me to do something i dont need to do.

i replaced the front o2 sensor after i put in the leaded gas but now it looks like ill need the new cat according to the code and auditech. i will most likely buy from labree cuz its $250 and techtonics has now gone up to $310.

pretty freaking frustrating taking this long to figure out the real problem...

[Tweaked]

Ok. Before we go any further, lets back up and review.

1. You used leaded gas. This destroyed your cat.
2. The car threw a P0170 code, a fuel trim code
3. You replaced the O2 sensors, but not the cat, and the P0170 code returned
4. A shop tells you the hose to your DV is torn, but you have not replaced it, even though you have a P0170 fuel trim code
5. You now additionally have a code for cat efficiency

So, not to be a dick, but based upon this info and the answers to these questions, why are you still running around with an MIL?

[A4speed]

MIL? my CEL is on but im not having any misfires (MIL = flashing cel right?)

i had the p0170 code, but when i used my vag com there was no fuel trim issue, just the cat code. this is why im confused as why i had the p0170 to begin with.

i have the 90 degree pipe that i can replace, maybe that will cause the cat efficiency to be better, but i dont see how thats possible.

[Tweaked]

MIL = Malfunction Indicator Lamp/Light. It's the correct OBDII term for "check engine light." Sorry, it's a left-over habit from working in a shop. CEL is forum speak. Same thing.

Replace the DV pipe. If it's torn, you have a leak. It will not, however, cause a cat efficiency code. Regardless, you should replace it.

As for the car efficiency code, run the SAI (secondary air injection) short test with the VAGcom and watch the O2 sensor voltage with a scope or quick-sampling voltmeter. If the voltage doesn't change, suspect the O2 sensor. If it does change voltage appropriately, replace the cat as it's likely fried.

But... If the car seems to be running fine, run a non-fouler on the post-cat O2. Erase the code and see if the code comes back.

[auditech79]

This is one of those cars where i wish i had it in person so i could just diagnose it in a day and get it over with. Yeah i stopped using MIL too because people on the forum don't get it. Tweaked has you on a pretty flawless diagnostic path so stick with it and see what you come up with and post back.

[A4speed]

yeah, its frustrating on my end too. i think i have to take the front bumper off so that pipe on the dv return line won't be such a bitch.

and i will check the voltage using vag com, hopefully the free version will read it since i dont have the full version?

im moving to Portland, OR tomorrow so ill have to find some time as i settle in. i will keep u guys posted, it just won't be right away.

[Tweaked]

This is one of those cars where i wish i had it in person so i could just diagnose it in a day and get it over with. Yeah i stopped using MIL too because people on the forum don't get it. Tweaked has you on a pretty flawless diagnostic path so stick with it and see what you come up with and post back.

Thanks man. I too want to bang my head against a wall sometimes, but I've was once on the other end many times while training. If it wasn't for patient teachers and coworkers, I would've been shot in college!

A4speed:

You don't have to remove the bumper to get to the DV, but it does give you a lot more room. If you don't have double-jointed hands, removing the bumper will make this a much easier task.

Keep us posted on what you find. Good luck with the move.