All information in this thread is taken from GolfMkV.com

If your car is stock and you still have warranty, then all the items below should be covered under warranty. If you are not stock, then the failed component may or may not be covered under warranty depending on what caused the failure, though this thread is not a warranty debate thread.

Disclaimer: This is a general guide only. Any problem with the car should be diagnosed by a competent and trained individual. All information provided is for information only and is not designed to replace a service manual or professional help. Use at your own risk.

1. Diverter valve failure

2. PCV failure

3. Broken intake ducting

4. Cam lobe wear

5. High pressure fuel pump failure

6. Air conditioning does not work

7. Tumble flap failure

8. Cold start problems

9. Misfires

1. Diverter valve failure

Background:

The stock diverter valve (dv) is prone to failure, whether chipped or stock. The diaphragm is prone to tearing (the orange shown in the pic of the stock dv (in the middle) below-may be a different color depending on the version of dv you have.)

Symptoms:

-A failing diverter valve will generally lose boost.

-The boost can be checked either via a boost gauge, or the vag-com (mb 115). You will see a huge drop in boost when the dv goes bad.

-Pin-hole DV failures usually allow boost to spike, but will then suddenly vent boost.

Tearing in the DV usually only allows 6-7 PSI. Boost will not spike.

-Alternatively, you can remove the dv, and inspect the diaphragm for tears. It is held onto the compressor housing by three bolts:

Solution:

-You can replace it with the stock dv, vw #06F 145 710 C. This is the latest dv as of this post, however, many people have also seen failures with the “C” dv.

-You can upgrade to the Forge DV #fmfsitv. Pics of the Forge DV are shown above.

2. Positive Crankcase Ventilation failure

Background:

The positive crankcase ventilation is supposed to let gases get sucked from the crankcase to the intake manifold when under vacuum. The problem is, when the pcv system fails, and allows positive pressure (boost) to go from the intake manifold back into the crankcase.

Symptoms:

-Typically you will see a slight drop in boost pressure. When my pcv failed, I saw a 2 psi drop across the board.

-Some oil will be pushed out through the oil filler cap, and onto the valve cover, and may possibly go towards the coil packs. There may also be some oil on the bottom side of the engine cover, where the oil filler cap is.

-There might be a slight decrease in MPG.

-Rear PCV failure usually results in oil accumulation around the DV, and will produce a little blue oil smoke at WOT applications.

Solution:

-There is the Digitalhippie fix which puts a check valve into the line from the crankcase to the intake manifold. For those who want a spare of the hose where the check valve is installed, the part number is 06F 103 221 F. You can read more about it here: http://www.golfmkv.com/forums/...=8952

-You can also upgrade to the latest PCV “G” valve. There have been very few failures reported with this PCV. Please verify the PCV you have before upgrading.

Part numbers for this upgrade:

PCV valve cover assembly: 06F 129 101 G

PCV valve cover gasket: 06F 103 483 E

PCV valve cover to turbo hose: 06F 103 215 A

PCV tube to turbo metal gasket: 06F 145 757 F

-If you did the DH pcv fix, and you have a rear pcv failure, then you will need to change the tube labeled as "Exhaust turbocharged gas outlet" showin in the pic above. the Part #'s are the last two shown above (06F 103 215 A & 06F 145 757 F)

3. Broken intake ducting

Background:

Some people have reported that part of the intake ducting that connects to the stock engine (the part in front of the accordion section) breaks off and gets lost, or worst, gets stuck and/or shredded by the fan. Due to its location, the loss in power should be minimal.

Symptom:

-You may notice that part of the ducting is missing.

-You may see shreds of the ducting in and around the fan.

-You may see the coolant temps rising possibly due to a part of the intake ducting getting stuck and not allowing the fan to turn. If the coolant gauge goes into the red, then immediately shut the engine off, and check to see if the fan is operating.

Solution:

-If the fan is damaged, then you may need a new fan.

-An aftermarket intake will replace the ducting section, and is a possibly solution.

-You might be able to tape or epoxy the sections together, so that it will make them harder to come apart. You may also remove the top piece alltogether.

4. Cam lobe wear

Background:

Excessive wear of intake camshaft lobe that drives the high pressure fuel pump. The wear limits maximum pump piston lift, causing fuel rail pressure fluctuations. The intake cam drives the fuel pump:

Please see also #5 below.

Symptom:

-Fuel cut-out when driving, esp. under WOT.

-Fuel cut-out symptoms range from soft pulsations of power to long-pulse bucking while in high-gear high-load situations (high gear at WOT, or up a grade). MIL may flash if cut-out is severe. Car will also go into hard-limp (no boost, 4500RPM limit) if severe enough.

-MIL ON

-P0087 Fuel Rail / System Pressure - Too Low

-P1093 Fuel Trim 2, Bank 1 Malfunction

-P2293 Fuel Pressure Regulator 2 Performance

Solution:

Increase surface hardening of camshaft lobe for the high pressure fuel pump. Improved intake camshafts have Part No. 06F109101B. Refer to TSB# 15 07 04

5. High pressure fuel pump failure

Background:

The high pressure fuel pump sometimes is not able to supply enough fuel, especially at low to mid range RPMs because it is cam driven. Please note that the high pressure fuel pump is different than the in-tank fuel pump. Please see also #4 above.

Symptom:

-Fuel cut-out when driving, esp. under WOT.

Solution:

-If you are chipped, then try to put the car in stock mode to see if the fuel cuts will stop. If it does, then you might want to wait until a fuel pump solution comes out. APR and Autotech are currently working on solutions.

-If you are stock, then it is possible that you have a bad fuel pump. The dealer should replace this under warranty.

6. Air conditioning does not work

Background:

The air conditioners manuf. By Zelex and Valeo tend to fail. They can be identified by the pulley:

Symptom:

- Air conditioning does not cool, air conditioning compressor may seize.

Solution:

- On the 2.0T engine a new Sanden compressor Part No: 1K0820803 index S must be installed. Refer to ETKA for the latest part # for the other engines. This should be covered under warranty.

7. Tumble flap failure

Background:

The tumble flap motor is prone to failure. This is probably the most common problem I’ve seen when scanning cars with the vag-com. A little background on how the tumble flap works:

Symptoms:

You may see the following DTC’s

-012599 - Intake Manifold Runner Control: Basic Setting not Completed

P3137 - 001 - Upper Limit Exceeded - Intermittent

-008196 - Intake Manifold Flap; Bank 1: Stuck Open

P2004 - 008 - Implausible Signal - Intermittent

- 012600 - Intake Manifold Runner Control: Regulation Deviation

P3138 - 008 - Implausible Signal - MIL ON

Solution: The intake manifold flap motor needs to be replaced.

8. Cold Start Problems

Background/Symptom: Troubles starting car when cold

Solution:

-Some people have reported that it was related to a certain gas, so maybe try a different gas station/company.

-Get the latest software reflash.

-Could also be a bad coil pack.

9. Misfires

Background/Symptom:

-Misfiring either under idle or under boost.

-Scan for DTC’s. See which cylinder is misfiring, and swap coils and or plugs to see if the misfire follows.

-Coil pack misfire (non-fire, lol) symptoms are shorter duration, rather violent, and also result in backfires from unburnt fuel entering the exhaust system. The MIL usually starts flashing. Car may or may not go into limp.

Solution:

-Replace coils and/or plugs

-Could be a bad fuel injector

Some good info there.

There are some more things to be considered when replacing the PCV so I would suggest anyone thinking of that might want to research it. AFAIK the part is an Audi part.

I have also attached the VW TSB for the cam lobe wear.

VW 20TFSI TSB Cam Wear.pdf

i hate to sound misinformed but item number 2..... isn't that an egr valve and not a pcv??

No it's known as the PCV Tom. That diagram is an official diagram

Just to add, the latest revision of the PCV valve cover assembly is now: 06F 129 101 L (Skoda).

Re:PCV fix/replacement

I just ordered the valve 06F 129 101 whatever the latest rev level is (not L anymore and didn't write it down when on the phone), plus the gasket. Do I need all four part numbers?