Front oxygen sensor replacement

Please post any and all trouble codes. what are the fuel trim levels?

I got a crank position sensor code once about 6 months ago, I cleared it and it has not been back. This latest code is bank 1 lean.

Its P0171. It started real out throwing that code once every few months to every few weeks, I would clear it, then it started coming back every few days.
Fuel mileage hasn't really changed and it doesn't seem to be running any different.
I cant get fuel trim levels with my little code reader. I would have to transplant my 5 wire oxygen sensor/meter from my Camaro I use to tune my Camaros carb to the bug.

16555/P0171/000369 - Ross-Tech Wiki

Before you start throwing parts at the problem: read the above link and start troubleshooting the list of possibilities; step by step, until you find the problem. Keep us posted; as your troubleshooting and repairs progress.

I was only going to throw the free new oxygen sensor on there, but the car has a 5 wire sensor, my free sensor is a 4 wire so that wont work.

Looking around yesterday evening waiting for it to cool off I did fix an air intake leak but the leak was forward of the air filter so I don't really think that could be it.
It looked like split plastic wire conduit that went to the air cleaner and didn't have a split or any wires in it. Just went to the bottom of the air cleaner from the large black thing under the intake manifold. What ever that black thing is, it seems to function on startup for a minute or so and what ever its doing makes the intake noise a little louder.

And the mass air flow has been messed with before, there are tool marks all over the clamp, like someone tired to use pliers that were too small to pinch the 2 tabs together to remove it. I know it wasn't me.

The bolt that holds the turbo inlet snorkel to the turbo is gone but it seems like the snorkel is firmly seated against the turbo and the bolt holes still look like they are lined up.

Now I have a P0300, 301 and 302 after taking it apart looking for a loose connection.

If the boost was leaking out of the piping between the turbo and the throttle body wouldn't that cause a rich condition?

All the 300 codes went away after I drove it, turn it off and restarted. I think when I hit the MAF with compressed air it may have knocked some dust or something off it.
Can I pull the MAF apart and hit it with MAF cleaner or electronics cleaner with out causing any problems?

I cant find any inward air leaks between the MAF and turbo inlet.

The crank case vent is between the MAF and turbo inlet, is there any possibility a broken dip stick tube or cracked rubber crank case vent line would allow more air to be drawn through the engine and into the intake between the MAF and turbo?

I have cleaned my maf with crc maf cleaner; with good results, undo the screws and remove the maf insert to clean (requires a torx plus 5 point security bit; got mine @ PepBoys CTA Tools Part # 9635 (5 Point Tamper Proof TORX PLUS 1/4 socket/bit: T25 size) for $5, it is Taiwanese but seems to be decent quality, not Snap On quality but for $5, what do you expect? This is a low torque situation; so, I think it will be ok for this situation. Some people; just use vise grips and then replace the screws with sheet metal screws and normal hex or phillips heads, that way you don't need a special tool.

Or just clean it; without removing the insert and just spray inside the tube, I remove mine (I figured it would be better to do it that way) but I'm kinda overkill!

Lots of diy's/videos for the 1.8T maf cleaning;

https://www.google.com/webhp?source...=1&espv=2&ie=UTF-8#q=vw 1.8T maf cleaning diy


https://www.google.com/search?q=CTA...ome..69i57&sourceid=chrome&es_sm=119&ie=UTF-8


This is a nice little maf testing article:

Part 1 -MAF Sensor Test: Jetta, New Beetle (5 wire type).

for the questions about rich/lean conditions: read this fuel trim info:

(reading/knowing trim levels, can help you figure out what is wrong: leaks or maf)

http://wiki.ross-tech.com/wiki/index.php/Fuel_Trim_Info

If you are new to the 1.8T; here is a great "faq" resource:

http://forums.vwvortex.com/showthre...uning-Modification-Assistance-Troubleshooting

I would really recommend; you get a basic vw scan tool/code reader like a vgate vs450 on amazon.com or go all the way, with factory level scan tool vcds from ross tech.

I have the T25 security bit. I will try some MAF cleaner.
My replacement dip stick tube will be delivered tomorrow and I will tape up the crack in the crank case vent line.

Good Ross Tech video on fuel trim:

https://www.youtube.com/watch?v=yM3iarhSP68&list=UUImxIy7LUUNeaWF54kcFvjw

I replaced the cracked dip stick tube. Then found a tear in the rubber PCV y tube and cleaned it up and sloped RTV.
When I started it up there was a change to how it ran. I drove and the engine was running real rough flashing the CEL and giving a p0302 code. Which went away. So there was air being drawn through those 2 openings for sure.
But then the P0171 code came back a little while later.

http://wiki.ross-tech.com/wiki/index.php/16686/P0302/000770

Looks like you were having a issue specifically; with cylinder number two. If you continue to have a rough running engine and the flashing light;
try swapping the coil pack, injector, spark plug, etc to another cylinder and see if the code follows the changes made; then, you know that component is the culprit. Replace the offending part.

http://wiki.ross-tech.com/wiki/index.php/16555/P0171/000369

Again I would start looking at the list of possibilities in the above link and start a process of elimination, until you hopefully find the problem.

Sent from AutoGuide.com Free App

The P0302 code only happens when I change something on the engine, like seal up an inward air leak. Other wise I never see it and it goes away completely after I restart the engine.
I changed the plugs last year about this time, because they likely had almost 70,000 miles on them.

It looks like I am running out of air leaks to seal up.

Glad you got it handled; what did the dealer charge you to diagnose the car? Did you then; do all the repairs yourself?


Sent from AutoGuide.com Free App