Suggestions on what to do from here? (1.8t 160hp)

 

AC refrigerant pressure switch, G395, that's a common issue. It could be the switch, it could be the LIN bus wiring from the switch back to the J519. Probably simple enough to just replace the switch and see where it goes from there.

What is this vehicle? B8.0 or B8.5? 1.8T, is that a Gen1 CAB, Gen2 CDH, or Gen3 CJE?

P0299, wastegate is loose? Would be the universal failure mode for the Gen1/Gen2 turbocharger unit.
Too lean, could be injectors, could be PCV (given the air system leak code). How long ago was the PCV replaced?
Oil pressure switches, hard to say without the measuring values for the oil switch status and oil pressure switch activation. Values should be 0 for activation and 3 for status, or 1 for activation and 1 for status. https://www.audiworld.com/forums/a4-.../#post25955893 The engine has no measurement of actual oil pressure, only "is there enough to trip this switch at pressure X", with the brown switch around 0.7 bar and the blue switch around 2.4 bar (iirc).

 

pcv tested it and seems to be working. I ordered high and low pressure switches and the ac sensor. The engine is a CAB. For the underboost i heard it could be due to the diverter valve? As far as the engine running too lean the engine management light went off and is now a passive fault when i scan the engine.

I do get the epc light on from time to time along with “do not exceed 4000rpm” and the switch off engine and check engine oil”. And have oil leaking from my driveshaft seal.

 

P0299 could be any number of issues. N249 recirculation valve, N75 wastegate actuator valve, but the most common issue is the wastegate linkage itself. The turbo for the CAB is generally the same as the turbo for all the longitudinal Gen1/Gen2 EA888 engines, be it 1.8T or 2.0T. So all the infamous CAEB P0299 wastegate issues, same for the CAB (CABA, CABB, whichever you have). CAEB is the US emissions version of the CDNC over there. On the recirc valve issue, the original 06F145710G used a diaphragm that would tear eventually. It was replaced by 06H145710D with a piston design. You could look at yours and see which you have. If it's 06F...G, then possibly. But if it's 06H...D, unlikely.

Do not exceed 4k is because when you go over 3500 rpm and the engine invokes high pressure mode, it's not getting a positive response from the high pressure confirmation switch (the blue one). You'd need to put a real oil pressure gauge on the system (use a T between the brown switch and the oil filter bracket, threading is M10x1.0) and see what the real measurements are. An oil pressure issue is likely the worst thing to have because it could literally be just about anything on the engine. Not sure what you mean by driveshaft seal. You mean the front main seal (crankshaft at front) or the rear main seal (crankshaft at rear)? "PCV tested it", oh? How did you do that? It could be in messing with the PCV you resolved an air leak.

If the situation has been updated, best to just clear all codes and see what comes back. This idea of gray passive and red active, not so convincing to me. Either the code is present or not present. There is an unlearning counter; that the unlearning counter is has made progress, is that suppose to be a flag for "passive"?

 

changed the air pressure sensor and know i have a new code


When i tried to turn on the air conditioning it automatically turns itself off. Any ideas what this is from?

 

You mean refrigerant pressure sensor, G395. Did you check the voltages at the 3-pin connector to be sure they look good? Should measure 12v from pin 3 (fuse) to pin 1 (ground). The 12v on pin 3 comes from fuse 12 in column black on the driver's end of the dash.
Measure the voltage from pin 2 to pin 1. Pin 2 is a LIN bus line operated by the J519 BCM (09-central electrics). You should measure some voltage, but it should vary from 1v to 11v depending on the bus activity level. You would need a scope to really see the waveform.
Could also be there was a defect in the Schrader valve under the G395 and refrigerant leaked out when the sensor was replaced? Or the sensor is just no good?

 

pin 3 is 12 v pin 2 is 9v. Is there meant to be some gas escaping when taking the refrigerant pressure? Because when i first took it off to clean and to replace no sound of gas escaping

 

No, there's a Schrader valve, just like your tire valve stem. So when you put the pressure sensor on, it's connected, when you remove it, it closes. Don't know then, the voltages look fine.

When you look at the measuring block showing the G395 pressure measurement, what do you see?
https://www.audizine.com/forum/showt...1#post14214555
15°C - 3+ bar
20°C - 4+ bar
25°C - 5+ bar
30°C - 6+ bar
35°C - 7+ bar
Those are AC off for a while, stabilized, values. Lower limit not reached implies to me the measured pressure is below the value necessary to invoke the compressor. You might need to have the refrigerant reloaded (the only correct way to have the correct weight of refrigerant is to evac the system and load the correct weight into the empty system). Might check first for leaks.