So i have had the P0171 running lean code for a loooong time now, and havent been able to fix it. I have taken it to an audi dealership and 2bennett audimotive adn neither have been able to figure it out. 2bennett just keeps trying to sell me more replacement parts thinking it is it, but none of them make sense for the situation. Well we picked up some code reader form a store and it now shows:

P0171 Secondairy Air.

anyone know what this is?

 

if you are running lean it must be a fueling issue or and o2 sensor issue. thye start throwing codes when they get lazy. so i would start with replacing the fuel filter and pump, since it is cheaper than o2 sensors and if that does not fix it see wich bank is reading lean and then simply replace the apropreate sensor.

 

I have a new O2 sensor but i am reluctant to put it on. And i considered those also, but looking at the symptoms, it doesnt seem proper. But it is having a secondary air fault reading issue. And i believe that is something to do with the recirculated air. anyone know what mroe specifically that is?

 

Usually when an O2 sensor starts to fail, and the ECU sees its readings becoming inaccurate enough that it won't trust them, it'll artificially richen the mixtureto safeguard the engine, rather than lean it out or trust the O2 sensor's readings and run the risk of engine damage. I'd suspect something besides O2s for this one, such as you mentioned for the filter. There are some sensors that could be freaking out too and causing the lean-run condition.

 

Well here it goes:

The engine goes first into limp mode then throws a CEL a bit later. This happens when i am at highway speeds (60-80 mph) and in fifth gear. so aorund 3-4k rpm. It only does it at high RPM's but it will stay in limp mode for a bit. It also does not matter how hard i am driving the car, i can keep goosing it, or i can leave cruise control on the whole time and it still happens. It used to happen every once in a while, maby 30 minutes into a highway drive every other drive, now it happens basically any time i take it above 60 mph for even a few minutes.

I have ruled out boost or vaccume leaks, i have cleaned the O2 sensor, i have a new coolant temp sensor to put in eventually.

When it goes into limp mode, the engine temperature guage goes to about 1 notch below the center. When it is not in limp mode, it sits basically in the center.

Also, before this started, i would spike at 21 psi and hold at around 18 ish. Now it spikes to maby 17 and holds at about 14.

I have been hunting this problem for such a long time, any help is wanted.

 

bump anyone?

 

it could be your MAF, o2 sensor, FPR, fuel pump, injectors, or a leak somewhere in the vac, intake, or secondary air system

 

allready replaced MAF. and the thing said Secondary Air, soooo im guessing thats it. i just dont know what that is

 

this might help....... when i had my 0171...... it was my maf, which it sounds like you replaced...... but on top of the maf,..... i was loosing boost preasure as well, come to find out it is the thrust sensor.... like maybe 50 bucks through the vw dealer, might be part of your problem, might not


here is what i would do/did..... went to the audi dealer... the mechanic put new parts on until, he couldn't get there to be a problem(fixed it).... if the part he put on didn't fix it, he took it off at no charge to me, if it fixed it, he told me what he put on and i told him..... not the service guys, that i was going to buy the parts and replace them my self...... being that it was the maf and thrust sensor...... 2 really easy parts to fix


might try that and see what you get......... that way you aren't spending a ton to throw parts at the car to still have an issue..... also most of those guys are cool...... and will tell you what is wrong with the car before they make you pay for it

 

Thanks, but what is a thrust sensor?