Jetta, Golf, and New Beetle new owner/buyer's/common issue checklist, for 1998-2006 TDI
back to 1000q: mk4 FAQ index
back to 1000q: pumpe duse "how to" list and FAQ

Introduction

Congratulations!  You just bought a new car, or at least a car that's new to you.  If you are thinking about buying a mk4 VW TDI, here is a checklist of common problems that should be checked and other basic maintenance items.  A full list of "how tos" is at 1000q: mk4 FAQ and "how to" index and 1000q: mk4 pumpe duse FAQ and "how to" index.

The first thing you need to know is if your car is "pumpe duse" or regular direct injection.  Generally speaking, 1998-2003 mk4 (4th generation) VW TDI are regular direct injection with the Bosch distributor pump, 2004-2006 are pumpe duse (for models sold in north america)
See 1000q: mk4 jetta cosmetic differences and 1000q: direct injection vs. pumpe duse vs common rail for more details.

Then refer to: 1000 answered questions: 99-2003 jetta specs
 1000 answered questions: 2004-2005 jetta specs
 1000 answered questions: 99-2003 golf specs
 1000 answered questions: 2003-2006 golf specs
 1000 answered questions: 1998-2003 new beetle specs
 1000 answered questions: 2003-2006 new beetle specs
to see the maintenance intervals for items such as the timing belt, coolant, oil, etc., and "how to" links.  Take a look through 1000q: mk3 vs mk4 differences to see what interchangeable parts or differences the mark4 4th generation cars have with other generations.  Also see  1000q: proper engine break in details for some insight into proper engine break in and why you should occasionally put the engine under high load/rpm.

For immediate inspection and priority service

Timing belt = varies according to the year/engine so refer to your model's page specific information, liked above.  Note that early cars can have the timing belt retrofitted with a longer interval timing belt with a 100,000 mile change interval instead of 60,000 or lower miles.  (I didn't write that it would last 100,000 miles, just that the change interval is 100,000 miles!)  If this part fails, the cylinder head will be damaged and in severe cases you will need a new engine.  This is because the TDI is an interference engine, meaning if the timing belt or timing belt roller/tensioner fails, the valves will hit the pistons and cause damage.  For 1998-2003 TDI engines, see 1000q: timing belt part 1 and 1000q: timing belt part 2 for a detailed procedure.  The automatic transmission cars have lower timing belt change intervals in some years because the larger injection pump puts more stress on the timing belt.  

Note - if you just purchased this car, many sellers will have the timing belt changed to add value to the car.  Many don't know how to properly index the tight tolerances that a diesel engine needs or the procedures for replacing the timing belt on a TDI.  Some have a mechanic who is used to gasoline cars work on a TDI engine and it gets messed up.  At least remove the timing belt cover and inspect the parts to see if they look new as some sellers will outright lie.  If you have any doubt about the timing belt, have it changed as soon as possible not as soon as practical!

Engine oil = 10,000 mile change w/filter if you are using synthetic engine oil for diesels.  See 1000q: diesel engine oil for a list of direct injection (non pumpe duse) engine oils.  See 1000q: pumpe duse engine oil for a list of oils approved by VW for pumpe duse engines.  Note that if you have a pumpe duse engine and don't use an engine oil that is "approved by VW for pumpe duse engines", they can try to reject warranty claims on the engine unless you have proof that pumpe duse oil was used!  Also note that it is normal for the oil to be black, even when new.  See the engine oil lists for more details.  

Plastic belly shield present? - While you are under the hood, see if the plastic belly pan is there, it's a black plastic shield that covers the bottom of the engine bay.  If you can see the ground through the engine bay, someone lost it.  It should be replaced to keep water and dirt off the bottom of the engine and belts.  If you see a metal shield, someone upgraded the plastic shield to protect the oil pan.  

Tire air pressure = as specified by the manufacturer.  There is a sticker inside the fuel door, on the inside of the driver's side door, or in the trunk which will specify an appropriate cold tire air pressure.  Check the pressure only when the tire is cool or you haven't driven the car in at least 5 hours.  A generic tire pressure you can use is 32 psi, never exceed the cold tire pressure listed on the side of the tire.

Engine coolant = lifetime coolant should be changed as necessary.  Note that VW/Audi G12 (G12+) or Pentosin coolant is red, pink, or purple.  Do NOT mix G12 with other colors (green, blue, orange) otherwise it can sludge the coolant.  If it has to be topped off, use distilled water.  If you are topping it off more than once, first figure out where the coolant is disappearing.  See 1000q: coolant flush to see a how to article on this. 

Fuel filter = 10,000 mile drain water, 20,000 mile replacement.  If you plan on using high percentages of biodiesel,  you should change it as soon as practical because biodiesel can loosen up deposits.    See 1000q: fuel filter change for more details.  See 1000q: intro to biodiesel for more info on biodiesel.

Check for coolant migration =  This is a bizarre condition where coolant will seep into the wiring harness due to a faulty coolant tank, traveling throughout the wiring harness and damaging electrical components.  This can total your car because in one extreme case, coolant seeped all the way back to the taillights and corroded all the electrical contacts!  See 1000q: coolant migration for more details.  It only takes 5 seconds to check.

Replace your relay 109  Some cars have a relay 109 that can fail, leaving the car suddenly off without explanation.  Relay 109 controls the ECU, so no ECU causes no fuel and the engine will suddenly shut off.   The old relay is black and marked "109" and is under the dashboard in the relay box.  The redesigned relay to fix this problem is gray and marked "109".  If you have a black relay 109, get it replaced ASAP with a gray relay 109.  A common symptom is the glow plug light not turning on.  Sometimes the relay will cool down, letting you start the car a few minutes after suddenly shutting off.  This only affects 2003 and earlier cars, 2004+ cars are not affected.

Diesel injection pump leaks - Due to age and fuel issues, the seals on the injection pump can leak.  The diesel fuel will corrode the timing belt and coolant hoses and even a small leak should be cleaned up asap.  The top cover, middle quantity adjuster section, and head o-ring can be replaced on the car, most of the other seals should ideally be done off the car and might need a rebuild with all new seals.  The pump should not be removed without locking the timing belt with VW timing belt tools.  See 1000q: injection pump top cover replacement for more details on top seal replacement.  Warning: only the top cover seal can be easily replaced, the other seals require a VAG-COM and/or at least basic mechanical sense.

Tandem pump leaks, for 2004-2005 mk4 cars only - The tandem pump is a dual fuel and vacuum pump on the driver's side of the engine head.  It carries fuel to the pumpe duse injectors and is found on 2004-2005 mk4 cars only (also used on mk5 cars) The earlier cars also had a pump but it was for vacuum only.  There was a recall on the tandem pump seal leaks.  If diesel fuel leaks onto the rubber parts, it will corrode the rubber hoses.

If the engine ever suddenly gives a lot of throttle on its own, immediately shut off the ignition and do not start it.  You can also put it in 5th gear and apply brakes as necessary and as safe, so make sure you don't cause an accident slamming on the brakes!  Through an engine malfunction, diesel engines could have an engine runaway which will cause the engine to race high by itself and self-destruct.  Immediately shut off the ignition as is safe and practical and take it to a mechanic before starting it again.  Read more about diesel runaway at 1000q: turbocharging - runaway engine.  All mk4+ cars have an "anti-shudder" valve which cuts off air to the engine and will shut it off.  Some people remove it and put in aftermarket "race pipes", I do not recommend this because it removes the emergency engine shut off feature.

Service areas that can wait and common problems

Get a VAG-COM and scan the car for codes.  If you plan on doing your own work on this car, you need a VAG-COM.  Note:  early VAG-COM software causes a conflict with the airbag module in 2000-2001 MK4 cars, possibly other years as well.  If you have a VAG-COM, upgrade it to the latest version, refer to the ross tech website for the final word on the airbag problem and more details at http://www.ross-tech.com/vag-com/vw_issues.html .  If you autoscan or try to scan the airbag module with earlier software, it will cause the airbag module to show and error and check airbag light on the dashboard permanently!

Apply the parking brake when parking!  It's good practice with any car but it is important on VWs because this sets the rear caliper self adjusters.  It's best to apply the brake before going into park (auto trans) or first/reverse gear (manual trans) to put stress on the brake instead of the transmission internals.

You may want to exchange the plastic lower engine bay shield for a metal shield if you live in an area where the suspension bottoms out on the road.  The oil pan is aluminum and it will crack if it gets hit from a speedbump, pothole bottoming out the car, or a tow truck driver's yoke hitting it.  If you hit a bump and notice the engine oil light turn on, STOP as soon as practical and check for oil leaks and the oil level.  There is a stronger steel bottomed oil pan available from VW.

A contributing factor to damaged oil pans is a worn suspension.  Replacement of the struts, strut mounts, and front anti-roll/sway bar bushings is recommended if your car has over 100,000 miles or as needed.  If your struts are worn out, the oil pan is more likely to bottom out on hard bounces and get damaged.  Also, people generally don't notice the mechanical condition of a used car but they do notice the body and how it rides.  Shiny paint and a good ride can make a tired car feel fresh.  Lastly, refreshing only a few components makes a big difference in restoring lost handling and adds safety in the event of an emergency maneuver.

The diesel fuel injection pump on 1998-2003 cars (pumpe duse cars have no diesel injection pump) can have the fuel temperature sensor malfunction, if you go to the dealership, they will try to sell you a new injection pump.  It is user replaceable, see 1000q: fuel temperature sensor replacement for a detailed "how to" on fixing this.  Pumpe duse cars also have a fuel temp sensor, it is on the fuel feed line near the tandem pump on the head.

Due to age and possibly the switch to ultra low sulfur fuel, some people experience leaking seals on the fuel injection pump (only for 1998-2003 models).  This will cause a no or hard start condition due to the fuel pump losing it's prime.  The dealership will not fix it, their only option is to replace the entire pump at great expense.  It's easy to change a few of the seals on the car as long as you have the right tools and basic mechanical skill.

The doors do not seem to recognize when the door was opened.  This is due to a faulty microswitch or broken soldering point in the door module.  The module cannot be accessed without removing the inside of the door, window, and window regulator.  Common symptoms include the door/alarm going off even after you open the door.

If the glow plug light is flashing, it could be a bad brake switch (under the brake pedal).  There were multiple recalls on the brake light switch under the brake pedal, the most recent part is green and may be a sign that the recall was done, call VW America with your VIN number to check for sure.  If you have an auto trans, a bad switch will not let you shift out of "park" since you normally have to brake to move the shifter out of park.

Replace the vacuum hoses because the ends get dried out, rub through, or crack.  They are mostly 3.5mm and 4mm hoses, you can buy silicone hose at Mcmaster.  These can cause limp mode, as if you are trying to use more power but the engine suddenly loses power, see 1000q: limp mode troubleshooting for more details.

The MAF (Mass air flow sensor) commonly fails.  Symptoms include a gradual reduction in power, stumbling, poor engine running.  The solution is MAF replacement.  This commonly occurs around 40-100,000 miles.  It is covered by an extended warranty for 7 years or 70,000 miles for pre-2002 cars.  See 1000q: MAF FAQ and 1000q: MAF replacement for mk4 and mk5 TDI.  I do not suggest the use of aftermarket "oiled gauze" high flow air filters because the stock TDI filter as plenty of excess capacity and the oiled gauze oil and dirt could damage the MAF sensor.

Do you have an automatic transmission and 1998-2003 model?  It uses the "01M" automatic transmission, expect lower fuel mileage.  It has also proven to be less reliable than the manual transmission.  Regular fluid changes should help but many feel that the problem is the design of the transmission because failures tend to not be related to wear.  The 01M shares many internal parts with the pre-1998 096 automatic transmission.  See 1000q: auto fluid change.  The 2004 and up auto transmissions seem to be better.  The good news is that problems seem to creep up rather than suddenly fail.  If you are experiencing a delayed reverse or delayed forward engagement, you may be experiencing the onset of automatic transmission failure, seek mechanical advice.

Don't leave the power mirror selector in the middle position if you have heated mirrors and a mk4 (1998-2005 and NB/Golf 2006) VW, leave the mirror selector in left or right.  The center position in most cars is "off", but on the VW it is "heat".  Leaving it in "heat" when the car is on will burn out the heated mirror element.  There is no timer to turn it off, it'll just always be on until it burns out.  VW has finally fixed this design quirk in it's newer cars by linking it to the rear defroster.  See 1000q: power mirror glass replacement if you want to remove the mirror glass and heater element.

The center console HVAC light often burns out.  Just pull out the center knob straight out to reveal the light bulb.  A picture can be found here

The turn signal/hazard switch had a recall.  The hazard switch is also the turn signal relay, it should have been replaced under recall or you can just pull the switch out and replace yourself.

The nut holding on the air conditioning compressor clutch pulley sometimes comes loose, if you are already down there, take a second to check it and tighten it to torque.  See pics and torque specs here:  1000q: AC nut fix

Other misc VW quirks and maintenance, non priority

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.  

You may also notice that the headlight plastic is oxidized and yellowed.  Polishing the headlights will make them clear again seen in 1000q: headlight polishing.

Is there wax like tar dripping from the bottom of the doors?  It is the wax sealant that VW uses to prevent corrosion.  It helps to prevent rust but it melts, coming out of the door vents.  Just use Goo Gone or some other paint-safe solvent and wipe clean with a microfiber towel and lots of water.  Why microfiber instead of a paper towel?  Microfiber is non-scratch and paper towels will scratch the paint.  The tar also has lots of dirt stuck to it so using a microfiber towel will help avoid scratches.  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 and is a separate display from the speedometer.

Brake and clutch fluid should be changed every 2 years with DOT 4 fluid.  See 1000q: brake / clutch fluid flush for some tips.

The dual mass clutch in the mk4 and up TDI has a higher rate of failure than single mass clutches found in earlier TDI.  The dual mass clutch uses dampers to make the car quieter and absorb vibrations that would otherwise go into the transmission.  This type of clutch is used in many modern cars and has a higher rate of failure simply because it's two parts instead of one.  It's nothing to be paranoid about but if you are removing the clutch/flywheel, it is suggested to also replace the dual mass flywheel.  You can also swap it out for a single mass flywheel and a clutch/pressure plate that can hold more torque, especially if you plan on power upgrades.  A single mass flywheel will not absorb the vibrations and will make noticeable chattering noises but can hold more power without stressing the dampeners in the dual mass flywheel.  See 1000q: VW TDI clutch FAQ for more details.

Stepping on the brake and accelerator at the same time will cause the drive by wire throttle to reduce power.  The Audi R8 exotic sports car also does it too, its a byproduct of drive by wire.  If you ever have an engine runaway, stepping on the brake should be the first attempt at stopping it.

The exhaust gas recirculation (EGR) system lets in exhaust which mixes with the oily crankcase vapors.  It forms a carbon buildup which will clog the intake.  1998-2003 cars seem to get this buildup and 2004 and up cars seem to not have significant buildup.  Some people believe that it is a result of ultra low sulfur fuel or more precise EGR operation, either way, 2004+ cars don't seem to be as affected by buildup.  Once build up sticks to the intake, it should be removed from the car for cleaning or replacement, do NOT try to clean it while it's still attached to the engine.  See 1000q: intake cleaning for the procedure - note, procedure is for the mk4 car, mk3 is similar.  Note that many people suggest turning down the EGR with a VAG-COM, but the ECU will adapt and the confirmed result is lower fuel economy.  

The EGR can also leak oil out the outside of the valve.  This causes an oily mess but it can also be a fire hazard if the leak is bad and a lot of oil gets onto the exhaust.  Previous TDIs had the EGR and intake manifold as one piece, luckily the mk4 cars have the EGR and intake manifold as two separate pieces.  EGR replacement is suggested.  See the above paragraph for the removal procedure or 1000q: EGR FAQ for general information on the EGR system.

The parking brake cables may also freeze the rear calipers in cold moist weather, so if the rear wheels seem to be stuck that may be the problem.  See 1000q: parking brake cable replacement for the fix.  If the rear brakes smell like hot and burning brakes it is probably the rear caliper sticking or a damaged wheel bearing.

The 1999-2002 cars with power windows can have faulty window regulator clips.  The power windows are held by a cable which is held by a plastic clip.  This plastic clip can break and cause the window to fall into the door without warning.  See 1000q: window regulator recall for more details.  This affects all years but only some years were covered by the extended recall.  Also note that after they switched to the metal clips, the metal clips can still fall off so it's recommended to glue them on.

Do the front strut mounts have a lot of play between the mount and it's seat?  Does the strut top stick up and does the strut fall down a little when you raise the car?  This is normal because some play is needed to allow the front wheels to turn.  As the suspension ages, you may notice a little more gap.

The driver's side handle tends to get scraped from use and lose it's "soft touch" coating.  The soft touch coating is a kind of paint to make the plastic feel softer but it always gets scratched.  To remove it, remove the affected panel and use a scrubber pad to scrape it off.  See 1000q: door card removal or 1000q: center console removal or 1000q: headlight switch removal for more tips on removing the affected part.  It also helps if you file your fingernails and use the pad of your fingers instead of the fingertip when touching the door.  Audi of the same generation also have this problem.

The front fenders will rust due to soundproofing that VW put between the metal fender and plastic wheel well liner.  You can prevent this from occurring by following the technique here or to view the TSB that VW released, 1000q: wheel well rust.  For some reason, it seems to show up on the driver's side before the passenger's side.  If you have a nice dealer, they will fix it for free, there are many confirmed reports of free dealer replacements.  The black triangular rear window trim on the jetta tends to rust for no good reason.  You can easily remove and repaint it.  See 1000q: triangle trim repaint for more details.

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.  Note that all mk4 cars have the variable vane turbo.  If it gets too stuck and causes a problem, it can put the car into limp mode, see 1000q: limp mode for more details on this issue.

If you are having engine problems, there is a rare chance that the ECU (ECM, car computer) could be the problem.  An ECU failure is very rare in any car but they seem to be more than very rare in the mk4 TDI ECU.  Again, this is still a rare occurrence, so check for coolant migration first and all other possible sensor issues first. 

That's all the most common notes with these cars, see 1000q: mk4 "how to" index and 1000q: mk4 pumpe duse cars "how to" index for a more comprehensive list of  how tos.

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