apenay

it came on about a month ago and when i scanned it then, it seemed to be just a loose gas cap problem. it had all the 17536 and 17538 codes but i was trying to be hopeful by clearing it to see if it goes away.

i scan it again tonight because the CEL came back on yesterday and this is what i got:

5 Faults Found:
17539 - Oxygen (Lambda) Sensor: B2 S1: Internal Resistance too High
P1131 - 35-10 - - - Intermittent

17536 - Fuel Trim: Bank 1 (Mult): System too Lean
P1128 - 35-10 - - - Intermittent

17538 - Fuel Trim: Bank 2 (Mult): System too Lean
P1130 - 35-10 - - - Intermittent

17831 - Secondary Air Injection System: Bank 1: Insufficient Flow
P1423 - 35-10 - - - Intermittent

17956 - Boost Pressure Regulation Valve (N75): Open Circuit
P1548 - 35-00 - -


so now i'm hoping that by cleaning the MAF the 17536 and 17538 codes will go away. but any ideas about the other codes?

i was doing some research about the n75 valve. where is that located? pics would be useful. if it says open circuit can it be just a fuse or wiring problem?

any comments of what you think may be the overall problems and some suggestions on how to correct it would be appreciated.


thanks for the help.

Epicman1

You can tell if they are going bad by squeezing and rolling the hose between your index finger and thumb. If the hose is dry rotting, it will crack and crumble inside the cotton sleeve. Audi cotton sleeved vacuum hoses should be replace every 4-5 years. A leaking vacuum hose will give you the same codes you are now getting...trust me I know..I replaced all hoses and it immediately corrected the problem.

apenay

also anyone know where the n75 valve is located?

thanks again

QCRAZY

You don't say but I would guess you have a 2000 based on your codes.

I see a bad O2 sensor, you may be able to fix this by just cleaning the connector or you will have to replace the entire sensor.

It also appears you have a bad MAF sensor.

You running a K&N by chance??

The seconday code is probably a bad vacuum line to the passenger side solenoid.

Check the connector and wiring to the N75. That's the only item that isn't intermitent. The N75 is a small brown "relay" looking item very near/below the accordian intake hose.

Epicman1

these are the small diameter hoses located mainly towards the front of the engine. I believe the n75 valve is the combi-valve, which operates the secondary air injection system. If there is a vacuum leak, this valve will cease to funtion properly.

apenay

...the car but i swapped it out right away with an oem filter. i recently put in another new one and cleaned out the air box as well.

i will try cleaning both the maf and the O2 sensors soon. although i think the O2 sensor may be a bit of a challenge to get to especially in the this weather and no garage.

n1mr0d

the n75 is basically the wastegate regulator on our car. ecu controls it to control when the wastegate sees boost pressure and opens.

DelMarA6

I hace a CEL problem, too. P0102 error downloaded by the emissions test shop, which I am told is a Mass Air Flow (MAF) sensor problem. He also told me the Oxygen Sensor warnings could be caused by a bad MAF. This could be your problem, the MAFs are notoroiously weak on these cars.

Brought my car to the dealer last night..awaiting their diagnosis.

apenay

do you know where is it located on the 2.7t?

apenay

in the middle. is there a special torx screwdriver that i need to use?