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Introduction
Change the fuel filter every 20,000 miles or as needed. Some pics from dweisel. All fuel filters linked from here are made by Mann or Meyle so don't worry about buying a "non genuine" VW part. In fact, Mann makes the OEM VW/Audi fuel filters.
Below
left is a new "Mann brand" Mann filter PU 936/2 (click to enlarge). The used filter
is an OEM VW/Audi filter 1k0 127 177 a (interchangeable with 1k0 127 434 a) with
the mark PU 936/2
and "Mann Filter". CAUTION - this 2 hole wide mouth filter is
not interchangeable with the one hole narrow mouth filter!
If you are using high percentages of biodiesel such as 85% or 100% biodiesel, you should expect to change it early since biodiesel will clean out the old buildup and clog the fuel filter if there's significant buildup in the fuel system. Your mileage will vary with biodiesel and the amount of buildup but as a safe rough estimate, change the filter at 1000 miles and then again at 5000 miles after using high percentages of bio. A more economical idea is to install a small clear inline fuel filter before the main fuel filter to screen out larger particles and let you see how clogged the fuel filter may be.
Early symptoms of a clogged fuel filter are stumbling at high rpm or lack of power. A general lack of power could also be limp mode, see 1000q: TDI limp mode and 1000q: can't rev or constant low power for possible causes and the solution. Make sure that these symptoms are not caused by an air leak in the fuel line or a clogged pickup at the fuel tank. Bacterial or algal growth in the fuel tank can clog the pickup. It's also possible that the low pressure in tank electric fuel pump, the lift pump, is failing or bad. This can cause hard starting or a stalled engine due to fuel starvation.
You may hear that the fuel filters are heated but this is a common myth - they are slightly warmed by the return line fuel and ambient heat off the engine. There is no active or electric heater unless someone installed an aftermarket heater for a veggie or grease system. You wouldn't want diesel or biodiesel to be too hot anyways.
The video below shows a really black used fuel filter. The older PD engines put some soot into the fuel. Your newer engine should not have any soot in the fuel so the used filter should appear much cleaner (brownish-tan).
2009+ TDI use 2 different fuel filters. 2009-2010 Jetta TDI built up to about 8/2010 used the 2 hole wide mouth filters (1k0127434 or 1k0127434a). 2010 VW Jetta TDI built after 9/2010 and 2010 Golf TDI should use the 1 hole narrow mouth filter 1k0127434b. The difference in the part number is no suffix, suffix "a", or suffix "b".
The difference in the part is 1 hole narrow mouth (filter B) or 2 hole wide mouth (no suffix filter and A). They use different housings and the 2 hole wide mouth filter is taller. I believe the difference in filters was due to rolling changes and parts availability during production. VW switched from one style, to another, then back to the first, and now I think they are trying to get rid of the leftovers. My opinion is that during the transition periods, which part equipped on your car could be as random as the guy on the assembly line grabbing something from the bin on the left vs. the bin on the right. Even though the 2010 Audi A3 TDI engine and basic chassis are the same as the Golf and Jetta TDI, it also uses a different housing, adding to the amusement.
2009 VW Jetta sedan and sportwagen and Audi A3 TDI use the engine code name CBEA. All others have CJAA engines. The fuel filters are not correlated to engine type.
If your fuel filter housing is filter #1 or #2, you use the wide mouth "2 hole" filter (they are interchangeable). If your filter housing is #3, you use the narrow mouth 1 hole filter, after reading this article refer to 1000q: 1 hole fuel filter change (2010 Golf TDI).. Filter #3 is shorter than the other ones so it's not interchangeable.
The wide mouth filter hosing uses the star shaped cap on #1 and #2 vs. the wide lip cap on #3. #1 has a bleed screw in the middle of the cap and the others don't. #1 also has a bayonet clamp so you can remove the housing by pulling it up and out. You can see it below the word "wide". The others are secured to the motor mount by 3x 10mm bolts/nut. Inside the housing, the filters for type "no suffix" and "a" showing in picture 1 and 2 sit around a black column shown below and come with the olympic ring seal. Type "b" shown in picture 3 is attached to the cap.
Filter #1: use VW# 1k0 127 434 or 1k0 127 177. The service manual says that some fuel should be drawn out of the torx screw drain but you will probably never find water. The other filter types don't even have drains.If your fuel filter housing is #3, use VW# 1k0 127 434 b or 1k0 127 177
b from kermatdi
The internal difference is in the filter height and internal construction. The wide mouth filter sits higher to make space for the water separator and
the narrow filter does not. You'll probably never find any water in the
fuel.
The filter housing with the bleed screw was disassembled to show the path the
fuel takes inside the housing by DanG144 and is mirrored here with permission (thanks!). Click the thumbnail image to open his .pdf file in a new
window.
The 2010-2014 Audi A3 TDI uses a different filter and housing even though it uses the CBEA engine. The housing is shown below. The fuel filter for 2010 Audi A3 TDI is # 3c0 127
434 (3c0127434). It uses
smaller torx bolts. In case you strip them, the torx bolt part number is Audi# wht 001 455.
Other than these 2 differences the replacement procedure is the same.
Parts (click links to compare current prices, some prices include shipping)
T30 torx screwdriver/wrench bit
VCDS cable from ross tech
paper towels
1 fuel filter. See notes above to confirm which part you need.
OR
20k mile filter kits (includes other misc filters, must include VIN when ordering to confirm correct fuel filter) kermatdi early A5 jetta, kermatdi later A5 jetta, metalman parts kit
Procedure
Safety disclaimer - you are working with open fuel lines and fuel vapors
when you change the fuel filter! Make sure that there are no sources of
ignition, spark, or open flames near the car or where fuel vapors could reach.
Work only in a well ventilated area where any fuel vapors can be immediately
evacuated and if fuel is spilled, clean it up before you continue working.
Although diesel vapors are not as flammable as gasoline vapors at room
temperature and pressure (as seen in the
video below at the 1:00 minute mark - it's a demonstration only, do not try
that yourself!), you still want to comply with all cautions in your factory
service manual. Wear eye protection at all times when working on your car.
See the TOS Agreement for the full legal disclaimer. Diesel fuel will melt
asphalt and rubber lines on your car so clean up any spills immediately.
Make sure to use gloves because diesel fuel has a strong odor and you don't want
it soaked into your hands.
The key should be off and the engine should not be running or else the fuel
system can be under pressure. Wrap a rag around the filter
housing to catch any fuel spills. If you spill any diesel fuel, wipe it up
because it can melt asphalt or rubber if allowed to soak. Here is a video showing the basics, please read all the notes here as well and ask any questions in the forum.
There are 5x T30 torx screws holding the filter housing and 1 torx screw for the bleed point in the middle. Loosen the bleed screw (if equipped) to help release any pressure and then remove all 5 torx screws to remove the cover.
The screws tend to get over tightened because they are only supposed to be
torqued to about 4 ft-lb. If they are stuck, put a drop of PB blaster or other
penetrating lubricant around the screw heads and let it soak. This will
make it much easier to remove them without risk of stripping the heads.
When you lift the lid, some fuel will splash out. There's a small notch at the 6 o'clock position where you can insert a pry to pull the lid up.
Check for metal flakes sitting on top of the fuel filter. A few CBEA/CJAA engines found in 2009+ engines had failed high pressure fuel pumps which disintegrated and sent metal flakes into the fuel system. Because the pump is downstream of the fuel filter, metal bits will also damage the injectors and pumps all the way back until it hits the fuel filter on the way back to the engine. If you see evidence of this, immediately document it yourself and at the dealer. Please upload pictures if you have experienced this.
Gently pry the old filter straight up using 2 screwdrivers. The bottom
will be somewhat stuck to the housing and if it pops out it will spill fuel everywhere.
Always wear eye protection at all times when working on
your car.
If you have a 2010 Jetta TDI or have filter housing picture #3 your filter should be the 1 hole narrow mouth filter. The filter and insides look different but the basic procedure is the same. Again, refer to 1000q: 1 hole fuel filter change (2010 Golf TDI for additional notes if you have filter type #3.
The top part (the cap) has the fuel lines connected to it. The bottom part is the canister.
Remove the old filter and remove the housing to pour most of the old fuel into the fuel tank. Some housings have tabs which let you pull the fuel filter housing
out - others are held with 2x 10mm bolts and a nut (visible below) holding it. Both are visible below. If you have canister type #1, the tabs (bayonet clamp) fit into these slots on the fuel filter bracket (removed for
illustration). If you have the other types, remove the 3x
10mm bolts/nut. The left bolt really only has to be loosened instead of removed if you have the non-tab mount because its hole is actually a slot. In the tab type it's a hole. The large silver metal thing is the passenger
side motor
mount.
The very bottom may be dirty so you can wipe the remaining fuel at the bottom out with a paper towel.
Clean out the housing and insert the new fuel filter. The new large green o-ring is for the housing cover. The blue "olympic rings" seal is for the fuel filter top. If you have a bleed screw there's also a metal washer under the screw. If you don't have a bleed screw ignore the metal washer that came with the filter.
Take clean diesel fuel and fill the fuel filter as much as possible. Diesel fuel is a lubricant and you want to thoroughly lubricate the high pressure fuel pump and injectors with fuel.
Replace the blue "olympic rings" and green filter cap seal. The blue "olympic rings" fuel filter seals will only fit into the recessed
housing one way. There is also a tab on the column which aligns the
cap to the column.
First tighten the cap/lid's T30 torx screws hand tight in a diagonal star pattern to keep it even, as if you were tightening wheel lug nuts. Keeping the lid even helps avoid pinching the cap's o-ring and causing a leak. If you have a cap with a bleed screw, tighten the torx screws to 2.2 ft- lbs. This is 27 inch lbs or 3 NM. If you have a cap without any bleed screw, tighten the screws to 3.7 ft lbs, or 44 inch lbs, 5NM. I don't know why the service manual states different torque settings for different filters so just don't over tighten them (let the o-ring do its job), check for leaks, and it should be OK.
With the engine off but the ignition key to "ON", plug your VCDS cable into the obd2 port and start the software.
Select "01-Engine".
Select "Output Tests -03".
Cycle through the tests and you will come to the below screens. Let the electric fuel pump
run for about 60 seconds. The service manual says to do this 3
times. You will hear it buzzing in the fuel
tank. Unlike earlier TDI, your fuel
tank's electric lift pump does not cycle on
when you turn the key to "ON". Therefore you must use VCDS
to purge air out of the fuel pumps and lines. While there's still fuel in
all the lines and injectors, there'll be lots of air too and common rail
injectors and high pressure pumps are not tolerant of air. (Diesel fuel is
an oil and lubricant).
You can also run the pump through Basic Settings. Go to block 35 and press ON and it will run both the in tank and auxillary fuel pumps.
If you don't have VCDS you can manually jump the pumps to run them and prime the fuel system. You should run both the electric fuel pump at the fuel tank (lift pump) and the aux boost pump before the high pressure fuel pump (HPFP). Here are some more pictures and a video.
Here are some thumbnails of the fuel pump terminals and the aux boost pump. (the picture on the right is with headlight removed for illustration to show the terminals)
Here are some notes from dweisel. Connect 12V jumper wires to the two large connectors. Apply positive to the one on the left (if you are facing the rear of the car), negative to the one on the right. Once you put power to the connectors the pump should run. The fuel sending unit pump I ran pumped approx. 128 oz. of fuel per minute. It took 15 seconds for the pump to fill the fuel sending unit with fuel when the unit was completely empty. With the pump sitting in about 1/2 of fuel a lot of foam was produced but the fuel in the line was free of foam.
On the back of the aux boost pump the +/- terminals are marked.
Connect jumper wires to the appropriate terminals and connect to 12v and the
pump will run. Priming correctly you need to run BOTH pumps at the same time for
1 minute for three times.
Do you have any other questions about changing the fuel filter on your 2009+ Jetta, Golf, or Audi A3 TDI? Please ask in the VW and Audi discussion forum here : myturbodiesel.com or search the site below.
Check for any loose fuel lines or tools. Start the engine and inspect
for leaks. The service manual also says to let the car warm up, and take a test drive,
pressing the accelerator all the way down at least once, and check for any leaks.
Below is a general picture showing routing of the fuel lines if you removed
them. Here is a video from 2009vwjettatdi showing some of these points.
I would not draw suction from the fuel filter drain screw (if equipped) because
it drains from the bottom, not the top so it will not help bleed air out.
I also suggest priming the pump as described earlier and filling the filter
housing with fuel. Pumping the pedal also will not do anything since the
car is drive by wire. Other than that, good video!
