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Discussion Starter #1 (Edited)
continued from part 1: http://www.myturbodiesel.com/1000q/b5/vw-passat-TDI-buying-guide.htm

Get the car detailed. You will be amazed at what a good paint polish and interior cleaning can do. See 1000q: car detailing index for more tips. There is a right way to wash/wax a car. If you go to an auto car wash, I suggest the touchless car washes.

The coefficient of drag is .27 for the sedan and wagon which is excellent to the point of mentioning it as a feature because it's one of the most aerodynamic cars of its time. By comparison, the same year VW Golf was .31. The Prius is .25.

Oxidization and yellowing of the plastic headlight lenses creates glare and looks bad. See 1000q: headlight polishing for details on cleaning them up.
VW uses an anti-corrosion wax sealant that can melt in the summer and drip out of the doors. It looks like waxy goo and sometimes makes a crayon smell in the interior. First wash off the dirt imbedded in the sealant and then use Goo Gone for auto paint or a paint-safe solvent to wipe it off. Follow up with soap and water, then wax. See 1000q: car detailing index for more detailing tips.

It's normal for the speedometer to read slightly higher than actual speed. German cars tend to have fast speedometers to account for car variations and so that they don't read lower than actual speed. The odometer reading should be correct for warranty purposes and is a separate display from the speedometer. If it bothers you, remove the instrument cluster and pop the needle off. Reinstall the needle a few mph slower and problem fixed. See 1000q: instrument cluster removal for details on a Jetta - your Passat is similar.

When you lock the car it's normal for the alarm to beep like a wounded goose honking into a can. It's not broken, it's supposed to be a quieter and less annoying sound than the horn. Audi also sound like that and the Passat uses many Audi parts. The horn is behind the driver's side rear pillar.
If the temperature drops below 39oF, you will hear a chime and warning on the instrument cluster display. This is to warn you that the road could have some ice.

There's a blocked off plug next to the battery which looks like it should be plugged in to something or is missing wires. This Passat mystery plug is for a device to keep the battery charged during shipping. It now has a dummy plug in it to close it off and you can't use it anyways. Click to open a picture of it in a new window.

If the lift pump (the low pressure electric fuel pump in the fuel tank) fails, it will cause low power or engine stalling. Some pump models cause engine stalling and others have a small bypass that will let the engine keep running at reduced power. If you hear a after turning the key to on but before starting the engine, this is the electric fuel pump in the fuel tank pressurizing the fuel lines. When you turn the ignition to "ON" (but before starting the engine), you may hear a gurgling/trickling fluid sound for about 1/2 second. You may also hear the electric motor humming in the rear of the car by the fuel tank. This means the fuel pump is working. If you don't hear anything sometimes it's broken and sometimes it's just quiet. Check the fuel pressure before the fuel filter to confirm the status of the fuel pump.

If you turn the key on, wait, and then turn it off, you may hear a high pitched whining sound from the engine. This is the electric EGR valve motor self calibrating and turning the valve. If you hear coolant gurgling behind the dashboard after you start the engine and start to move, it's air in the coolant system getting trapped at the high spot, the heater core. First check the coolant level - if low, find the leak. If not, bleed the air out, see 1000q: coolant flush for details.


The sunroof has a full open and full-full open position that isn't obvious.

The sunvisors slide out as an extra adjustment. There's also a mini visor at the front of the center console for the little space above the rear view mirror.

If the doors were locked, the front doors will open with the first pull of the interior door handle. The rear interior door handles require 2 pulls - the first unlocks the door. The second pops the door open.

Never put your keys in the trunk because if you open the trunk, put your keys in with some bags, etc., and then close the trunk, the doors will be locked with the keys in the trunk.

The brake fluid should be changed every 2 years or as needed with DOT 4 fluid. Do not use DOT 5 fluid. See 1000q: brake fluid flush for some tips.
It's normal for the engine to lose power if you step on the brake and accelerator at the same time. This is because the accelerator pedal is drive by wire throttle and for safety reasons, brakes should always be more powerful than the engine. If the engine every suddenly revs high on it's own from a runaway (see above for the explanation), stepping on the brake should be the first step.

An error code that is getting more common is air intake flap (like a throttle) failure. It does not affect driveability at all but will throw the CEL/MIL. It can often be fixed by unscrewing the top cover and gently prying it off, then cleaning/slightly bending the contacts.

The Passat uses 10mm nuts to hold the engine cover to the engine. Other cars used ball-socket snap covers that just pull off, making engine inspection much easier. You can retrofit the snap covers to your engine cover, see 1000q: pumpe duse cover mod for details. It's for a Jetta but it works the same way.

After high miles, carbon can buildup on the inside of the intake manifold. They form because the exhaust gas recirculation system (EGR) lets in exhaust which mixes with oily crankcase vapors. This was a bigger maintenance issue on older cars. Newer TDI have more accurate EGR metering and the introduction of USLD diesel also helped reduce buildup. If there is significant buildup, you must remove the intake manifold to clean it off. Do NOT try to clean it on the engine because it'll send carbon chunks into the engine and turbo. See 1000q: EGR FAQ for general information on the EGR system.
Repeated removal of the intake hoses can wear down the clips. If you find that the clips pop off, use an aftermarket clamp to hold it down. Here is a one from kermatdi.

All mk4 cars had problems with cracking power window regulator clips. If they break the window can fall down into the door and get stuck. See 1000q: window regulator recall/repair for more details.

Many people have problems with the lower intercooler hoses wearing through. The way the cars are assembled from the factory, a thick chassis ground wire may rub against the rubber hose. To fix this, loosen the ground wire end and rotate it out of the way. Here is a picture with the bumper and radiator off showing the hose and one of the ground wires. You only have to remove the splash pan to get access, you don't have to remove the bumper. Check both the left and right sides.


While it's not a common problem, some fan clutch bearings have worn. This makes a howling sound at the front of the engine that is rpm and not speed dependant. The same bearing is used on Audis. The alternator clutch inside the alternator can also wear. With the belt off, use a wood stick to counterhold the fan inside the alternator to hold the shaft steady. The pulley should rotate freely in one direction and not in the other.
Some poor quality rebuilt or aftermarket axles or CV joints will cause vibration when in drive/reverse/in gear that goes away once it's in neutral. See 1000q: CV boot replacement for a video.

The foam soundproofing at the top of the fenders rubs and causes rust on some Jetta and Golf. mk3 and mk5 also have foam at the same exact place but they don't seem to have this problem. Trimming the corner of the foam will prevent any possible problem. See 1000q: fender rust solution for the repair.
Use the pad of your fingers instead of your fingernails when touching the door handles. The soft touch coating on the door handles tend to get scratched up.

The soft touch coating makes the plastic softer but it tends to get scratched from fingernails or melted from certain hand lotions/sunscreen. To remove the coating, just remove the handle and scrub it off. See 1000q: door card removal for pictures and tips on removal.

The variable vane actuators in and around the turbocharger can get stuck, causing too much or too little (normal failure mode) turbo boost. There is a lever on the outside of the turbo which can rust or seize and levers inside the turbo which can get stuck. The best way to prevent this is to occasionally put the engine under high load/rpm once the engine is fully warmed up to burn up the soot and heat up the exhaust gases. See 1000q: proper engine break in for more details on why you should occasionally put the engine under high load/rpm. All mk4 cars use a variable vane turbo. If it gets too stuck and causes a problem, it can put the car into limp mode or cause low power. See 1000q: limp mode , 1000q: low power fix, or 1000q: VNT actuator fix for more details on this issue. (some tips are for Jetta but same idea).

Some cars have had bad torque converters. Here is how to test for it:passat-torque-converter.pdf

You can disable autolock of the doors at about 10 mph, set all doors to unlock with a single press of the key fob (instead of first press unlocks driver's door, second press unlocks all doors), or set all doors to unlock when you remove the ignition key. Just change the code in the comfort convenience module using a ross tech VCDS cable through the or the dealer can do it. (should only take 10 minutes) See http://www.myturbodiesel.com/1000q/b5/vcds-mods-vw-jetta-golf-new-beetle.htm for more details.
 

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Discussion Starter #4
Added a note about putting your keys in the trunk. No it didn't happen to me, I just thought about it and decided to add this warning.
 

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Discussion Starter #7
They are completely different, no relation. So far, they are proving very reliable with the exception of a few turbo failures under warranty.
 

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Hey, my wife's 2005 Passat tdi wagon with 137K miles, was down for 3 weeks. The problem was that the ground wire had rubbed through the lower inter cooler hose, just below the turbo. Took me a while to find it. Wish I had read this thread, first. Here was my process.
Car was being thrown into limp mode. Trouble codes for turbo under boost (P0299) and Mass Air Flow(MAF) sensor were being thrown. I read everything about limp mode on this forum. I cleaned my MAF sensor with MAF sensor cleaner. Didn't work. I replaced MAF with genuine Bosch, and air filter, that didn't work. I used ross-tech VCDS to measure intake manifold pressure requested versus actual. Clearly, my actual pressure was always averaging about 150mbar's below the requested pressure. I figured out how to measure this, here http://www.myturbodiesel.com/1000q/multi/low-power-fix-TDI.htm , it is Group 11 of measuring blocks.

I removed the intake manifold, egr valve, and intake flap, and totally cleaned out all the years of caked diesel soot. I mostly used oven cleaner, carb cleaner, screw drivers, rags and pressure washer. I tried redneck method, but couldn't get that to work properly. Even put a 'doggie collar' on the hose going into the intake flap. Also replaced the N72 pressure regulator valve and vac lines. Purchased a new VNT actuator, but determined mine was fine with mighty vac. Will save VNT for another time. Put it all back together, car had same problem. I would post photos, but when I try to copy them into this message, it yells at me, that photo is too large, even after I shrunk to small size.
Then I pulled lock carrier off car.
(would like to post photo here)
And after removing the turbo, I found this.
(would like to post photo here)
Here is the ground wire.
(would like to post photo here)
I flipped the ground wire over, so it would no longer rub.
(would like to post photo here)
I then taped up the inter cooler hose, with a layer of hose tape, gorilla tape, and duct tape.
(would like to post photo here)
Here is the hose placed back on the turbo.
(would like to post photo here)
While I was at it, I also replaced the turbo intake oil line, with a pretty steel braided one. Broke the old one, while removing it. Cut a slot in one of my 17mm wrenches to tighten the new line on the turbo.

Put it all back together, car started like a charm, ran great for about 5 miles... Then back into limp mode, again... Lesson learned: tape does not hold up to hot turbo gasses at 20psi.

Replaced hose with new one, ~300 bucks. So far so good.:)
 
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