Bare with me, this is a long one haha
Ok so my car randomly popped some CEL's over a month ago.
P0174, P0171- Lean Bank 1 & 2
P1504- Bypass Leak
Also noticed the engine oil cap had some milky residue on the bottom as i checked my oil soon after (no residue on dip stick or am i losing coolant). My first reaction was coolant but again it is not dropping. Now the guy in autozone told me sometimes cars will do that in the extreme cold conditions from condensation build up? Note: This all happened after a below 0 degree night. Coldest the car has ever seen (florida car).
So I had autozone reset the codes for me. I ran some Complete fuel system cleaner through it. And it has ran like butter for the past month and it appeared that the milky residue cleaned up around the oil cap. Another cold night last night.... And it threw the same three codes again. And the milky residue appeared again.. idk if that has anything to do with it but yeah. So i plan on running more system cleaner. Already cleared the codes and have went 10 miles without it popping back on. I want to clean the MAF sensor also if anyone can give me a quick DIY on that.... Also any other opinions would be greatly appreciated. Thank you. And BTW the car has ran perfectly fine through all of this. Also this is the first time the car has done this to me since ive owned it. And i just recently switched to 5w30 fully synthetic for the winter.(its first time running that weight). About two weeks before this all started to happen. possibly related?

 

bump.. anyone?

 

please?

 

Bump for ya.

 

Bank 1&2 lean codes could be a number of things. I've been chasing a bank 1 lean code myself, its proven quite difficult to diagnose without any other codes to accompany it. Could be MAF, primary O2 sensors, spark plugs, etc. Unless you're into just randomly buying and replacing parts, I'd suggest you just let it go for now and check it every week or 2 until something else starts throwing codes. If you have access to a VAG-com, that would be the better way to go about diagnosing this.

P1504- Bypass Leak sounds like the idle air control valve right at the throttle body. Thats this little guy.

As for the milky stuff you're seeing in the crank case, could be the cold weather. If your head gasket or oil cooler were leaking, there'd also be oil in the coolant, which you'd be able to see in the expansion tank.

 

Also, check for vacume leaks, and clean out the little "Y" pipe that is located in the 3/4" plastic serrated hose. Just be very careful with them as the tend to get brittle. This is all part of your crankcase evaproative system. I would be willing to bet that your plastic hoses are full of the gunk you found on the bottom of your oil cap, and the little "Y" piece has quit functioning because of all the gunk. this will cause moisture build-up inside your engine.

460

 

Awesome thank you very much guys. And if its not asking too much... does anyone have a picture of this Y fitting. like where it is located... i have no clue. thanks