Changed the upstream O2 sensor (mechanic thinks it’s the downstream now) but the other 4 codes popped up

[kristen_1819]

Any idea why these last 4 faults are showing up? Mechanic is booked up and very far and I'm not sure how urgent this is

 

[ROH ECHT]

I would first rule out the air inlet system has no leaks. Seeing an under-boost code and a rich code together, does suggest a leak between the turbo and inlet manifold. Find another tech; one who doesn't replace items simply based on fault codes, and actually searches to discover the reason. None of those codes suggest anything is wrong with the B1S2 O2 sensor. They are all Lambda based which is reported by the B1S1 O2 sensor that was replaced.

 

[kristen_1819]

I would first rule out the air inlet system has no leaks. Seeing an under-boost code and a rich code together, does suggest a leak between the turbo and inlet manifold. Find another tech; one who doesn't replace items simply based on fault codes, and actually searches to discover the reason. None of those codes suggest anything is wrong with the B1S2 O2 sensor. They are all Lambda based which is reported by the B1S1 O2 sensor that was replaced.

Last time he did a smoke test and said it was <1 psi of air that was coming from the dipstick which needs to be replaced (the suction is gone). Could that possibly be it? Can you explain what you mean by "They are all Lambda based which is reported by the B1S1 O2 sensor that was replaced?"
A few months prior I had VW check the fault codes and they said everything with turbo was fine and that's a shadow code, same like the mechanic I go to has said.

 

[ROH ECHT]

"was <1 psi of air that was coming from the dipstick which needs to be replaced (the suction is gone). Could that possibly be it?"
Well, that is an air inlet leak and there could be more not yet discovered. When it is not in boost, the inlet manifold and PCV allows the application of vacuum to the crankcase. So if the crankcase isn't sealed, then it creates an air inlet leak. There may also be an issue with the function of the PCV. Someone familiar with this system needs to look at it. Because there are two styles of PCV and two rear vent tubes needing to be paired properly (proper pairing shown in the pic below). If someone mismatched those two in the past...this could be a part of the issue.
Lambda, or air-fuel ratio, is what the B1S1 O2 sensor (the first upper O2) reports to the ECU.

 

[kristen_1819]

This helps! Would the smoke test from last time show this? The same code is pooping up so I can assume its the dipstick holder? But its such a small area to set off that code...we are checking the wastegate and the n75 sensor as well

 

[ROH ECHT]

This helps! Would the smoke test from last time show this? The same code is pooping up so I can assume its the dipstick holder? But its such a small area to set off that code...we are checking the wastegate and the n75 sensor as well

Well the dipstick, yes if not sealed, will cause an un-metered inlet air code.

The N75 is a valve. If the N75 is cracked or has a leak in the hoses; this too could cause an un-metered inlet air code.

It's tough to say what would've shown, or to assume anything, when another has done the leak detection with a smoker. Because we, out here, don't know if they properly tested all systems to include testing the other side of one-way valves; which shut when vacuum isn't being applied by the inlet manifold.

 

[kristen_1819]

Well the dipstick, yes if not sealed, will cause an un-metered inlet air code.

The N75 is a valve. If the N75 is cracked or has a leak in the hoses; this too could cause an un-metered inlet air code.

It's tough to say what would've shown, or to assume anything, when another has done the leak detection with a smoker. Because we, out here, don't know if they properly tested all systems to include testing the other side of one-way valves; which shut when vacuum isn't being applied by the inlet manifold.

Thanks, I will ask. Having the mechanic check the N75 and DV as well. He owns 4 gtis so I trust him completely.

 

[kristen_1819]

Well the dipstick, yes if not sealed, will cause an un-metered inlet air code.

The N75 is a valve. If the N75 is cracked or has a leak in the hoses; this too could cause an un-metered inlet air code.

It's tough to say what would've shown, or to assume anything, when another has done the leak detection with a smoker. Because we, out here, don't know if they properly tested all systems to include testing the other side of one-way valves; which shut when vacuum isn't being applied by the inlet manifold.

Turned out it was the DV! After the tune it must've gone out. Car runs perfect now!