Dedicated to my first car–a Titanium Silver 2003 BMW E46 330i–and the lessons I have learned throughout my ownership experience, from 2008 and on .. and on .. and on ..

The good

It’s an excellent car with a massive, supportive community and a healthy aftermarket.

The bad

Problems on the BMW E46 are many, and having it maintained exclusively at the dealership is a costly proposition. Every owner knows this.

The window regulators, cooling system plastics are suspect to failure, VANOS seals (for +TQ), the subframe issue (though this problem is more or less limited in scope to the earlier E46), the oil level sensor, final stage unit (aka final stage resistor / FSU / FSR), tail lamp wiring (recall issued by BMW NA) … you can fix all of these things, and then it can still become a noisy little car overall.

Getting familiarized with the basics as needs arose proved to be challenging when parts began failing. Looking back, there were many ways to go about this that would have alleviated headaches down the road in the future, but at the time thoughts about preventative maintenance were in the very back of my head. I risk sounding like a stodgy old man, but you really want to budget for maintenance before looking into go-fast and cosmetic modifications. Nothing is sexier than a clean, running car.

My Notes & Opinions On..

BMW Performance Parts for the BMW E46 – Performance accessories from BMW – some of these parts are hot; I’ve scanned the BMW Performance catalog for the BMW E46 for your pleasure. You can download the PDF that I stitched together.

Front Control Arm Bushing (FCAB) – OE-style, M vs. non-M, and Aftermarket (Work in progress)

Rear Trailing Arm Bushing (RTAB) (Work in progress)

Fluids and shit

Using BMW Scanner on the BMW E46 to Read and Clear Codes (do a heck of a lot more than reset your oil service indicator)

My notes just scratch the surface, but I hope you find them useful.

Things I’ve Done

Resources That Will Take You Far – parts diagrams & part numbers for BMW
A visit to a BMW VIN decoder

Things That Go Wrong

Broken Window Regulators
Leaves you stuck with your inoperative window in the down position. One of my regulators failed catastrophically, and the window tint got scratched. Zip ties can be used to shore up a working regulator, and they’re a good preventative measure.
Warning signs sometimes are a noisy crunchy sound a few times before you lose control of your window.
Pay particular attention to your door seal when reassembling if you want to avoid rain soaked carpet in your car!

Lower Control Arm Bushing Failure
Common symptoms for torn or cracked lower control arm bushings are undesired front toe changes during cornering, vague and rubbery feel in the steering, and vibration experienced while braking at freeway speeds. Non-M bushings are commonly replaced with M3 bushings to increase performance with little to no change in comfort.

Tie Rod Wear
Symtoms include: steering shimmy, clunking during steering input and inability to hold proper alignment. If any of the ball joint boots is cracked (you’ll see grease coming out) then expect that component to need replacement. All components should also be checked for excessive play, and replaced if out of BMW spec.

Worn or Blown Shocks and Struts
Factory BMW shocks work great for about 30k. By 60k they are completely shot. Most folks who have been driving their cars since new hardly notice the deterioration as it is gradual. Symptoms include: diving under braking and acceleration, excessive lean and suspension compression during cornering. Bouncy and uncomfortable ride. Shocks and struts may visibly leak shock oil.

Worn or Failed Swaybar Endlinks
Worn swaybar endlinks can compromise handling. A worn swaybar can sound like a metallic clicking noise. There is no critical danger in a failed swaybar endlink, but the handling of the car is severely compromised.

Torn Rear Trailing Arm Bushings (RTABs)
E46’s are prone to the same RTAB failure as the E36. In fact, since they are heavier cars, they tend to wear faster on the E46. If the rear of the car feels strange during cornering or you have excessive rear tire wear, expect that your RTABs are shot. Typical mileage for the E46 is around 35-45k. Failure to replace could lead to torn subframe and costly repairs. EDGE recommends replacement with factory units and RTAB limiting shims (search for RTAB limiters). The shims prevent excessive movement and can double the life of the bushing.

Torn Rear Shock Mounts
Torn or destroyed rear shock mounts will produce a very pronounced clunk during any sort of suspension movement, and could possibly just tear right through the trunk carpeting into the passenger cabin. Sloppy and erratic handling and excessive rear suspension play are common symptoms of a RSM failure.

Torn Subframe and Subframe Bushings
Torn subframe bushings could lead to subframe failure. Common symptoms of subframe failure are erratic handling and unidentified clunks and bangs from the rear of the car. Early detection of a torn or cracked subframe bushing can prevent costly subframe repair and welding. We see subframe issues mainly appearing in tracked and autocrossed E46’s, but we have swapped out cracked bushings in higher mileage E46’s as well.

Torn or Cracked Transmission Mounts
Torn transmission mounts could lead to the dreaded ‘money shift,’ or mechanical overrev and the possible (and likely) destruction of the car’s motor. Worn transmission mounts allow for an excess amount of transmission movement. Symptoms can be hard, notchy and forced shifting during cornering, excessive shifter jerk during hard acceleration and braking, and muddy shifter feel.

Ripped or Failed Guibo
A torn guibo (Flex Disc) will result in a perceivable ‘drivetrain elasticity.’ Acceleration will be preceded with a loud clunk as the guibo bolts bind together.

Dirty Automatic Transmission Fluid or Clogged Filter
Hesitation and/or hard shifting could be the result of dirty and old automatic transmission fluid or clogged transmission filter.

Cooling System Plastics

Water Pump Failure—–extremely common & tragic
Water pump failure is without a doubt the easiest way to cause extensive and expensive damage to your BMW. The main symptom will be a rapidly overheating motor. What occurs is that the bearing or impeller on the stock pump breaks, completely disabling the cooling system. If you ever see the temperature gauge on your BMW climb above the 3/4 mark,…


Failure to catch the overheating motor in time can result in a warped head or even more severe engine damage. Change out the water pump every 60-80k miles.

Cracked Radiator Necks
BMW loves their plastic radiator tanks….Unfortunately…The plastic around the radiator necks become brittle and crack with age, often without warning. Radiators should be thought of as 80-100k mile wear items.

Fan Clutch Failure
Most fan clutches fail between 80 and 100k miles. They provide the primary cooling for your car, and are easy for us to diagnose.

Accessory Belt and Tensioner Failure
Worn tensioners and idler pullies will sound like a squealing noise from the engine bay. Belts should be inspected for cracks regularly. If a belt happens to snap, the cooling system will fail as the water pump will cease to operate. Power steering and the alternator will also fail to work. Again, pull over and shut the car off immediately should you suspect a belt failure or see the temperature gauge rise past the 3/4 mark.

Leaky valve cover gasket
Prevalent on all BMWs, a burning oil smell could indicate a leaky valve cover gasket. If the condition continues unchecked, oil can seep into the spark plug holes and damage the ignition coils, resulting in costly replacement. Replacement of this inexpensive gasket is a good idea when changing sparkplugs as the coilpacks will already be out.

Vanos seals. See for details for explanation, symptoms and upgraded parts.

Oil Filter Housing Gasket leaks. $6 part requires removal of the housing for replacement.

DISA is pretty high up on the list of high fail rate components. German Automotive Solutions sells a repair kit, as well as new DISAs that come fitted with their kit.

Tail light ground circuit fix (recall on this)

Sunroof – what a disaster that design is with leaks and jams and broken clips. Labor on this one is torture.

Door locks can break. If your locks unlock and windows all roll completlely down by themselves spontaneously, replace the driver’s door lock mechanism.

O2 Sensor Failure
Poor mileage, poor idle and flat spots in the power curve could be caused by bad O2 sensors. Even if your car isn’t throwing a check engine light, they may not be performing optimally. BMW recommends replacing the O2 sensors every 100k miles. Extended high-RPM running/racing and high-performance chips may shorten the replacement cycle.

Oil Separator
Non M cars. If you have a poor idle and periodic Check Engine lights, you may have a bad oil seperator. This valve tends to go bad and introduce a vacuum leak which produces the above symptoms and will eventually strand you somewhere. We started seeing these a year ago and we are now repairing more and more cars with this problem. Typical mileage seems to be around 80k. The good news is that the part is only around $75..the bad news is that the labor runs about 4 hours, depending on the year of the car.

Clogged and dirty pollen filter
If the flow of air out of the air conditioning and heater system is not as strong as it used to be, it strongly suggests the pollen microfilter of your car has become dirty and clogged over time. A damp and musky smell can also indicate a dirty filter. This is a service II replacement item.