E46 Home

Models

Interior

Options

Tourings

Convertibles

Compacts

Gallery

Mechanics

Problems

//M Car

Tuners

 

BMW E46 Three Series - Problems and Common Faults

Body and Fittings

It's far too easy to hit the button on the remote for the boot and open it by accident.

Electric windows are a common problem. The plastic clips break and the window slips out of the holder.

If doors stick shut in freezing weather put petroleum jelly on the rubber seals lightly.

If the headlights seem poor it could just be oxidisation on the base of the bulb or connectors. Osram Nightbreaker bulbs will amaze you and are worth the price, same wattage and perfectly legal.

If headlight glass becomes pitted if can be sanded back with special cleaning kits from the likes of 3M.

 

BMW E46 lights

Restoring your headlights isn't hard (E36 shown).

Don't suffer with scuffed bumper strips, new ones are cheap and easy to fit The same goes for wheel centre badges and the car's hood and trunk badges.

The rear of the rear wheel arch is always the first bit to rust, just like the E36. But overall these cars don't rust much.

If the windows start rising slowly try some silicone spray in the runners.

Check the drain holes in doors and other panels don't get blocked as the water build up will cause rust.

If the rear wiper is slow on a touring it may not be the motor but the bearing in the glass panel. You'd be astonished how stiff these can get. They can sometimes be partially stripped and greased to solve the problem.

If your touring clunks on bumps check for metal to metal contact between the bottom of the hydraulic struts that hold up the tailgate the bump stops on the body. The plastic cover eventually wears out.

Subframe mounts can fail on any model but particularly the M3. See the bottom of the M3 page for details.

Jacking the car isn't as easy for the home mechanics as on the E36. The older car had four positions for it's jack with dedicated pads underneath. The E46 uses the same jack as the E39 with it's rectangular mounting points. It's great if you want to jack one corner but it pushes the car to the side as it rises and this is a real problem if you want to raise two corners. Before you could raise the car with the jack then put an axle stand under the pad. Now there's just the pad so once you've raised it you're left searching for a safe position to put the axle stand (NEVER work under a car held by the jack alone).

Engines

BMW m40 engine

M43TU

Four cylinder 8 valve

1.6, 1.8 and 1.9

1988 - 2001

BMW m52 engine

M52TU M54

Six cylinder 24 valve

2.0, 2.2, 2.5, 2.8 and 3.0

1989 - 2005

BMW n42 engine

N42

Four cylinder 16 valve, first Valvetronic engine

1.8 and 2.0

2001 - 2004

BMW m57 diesel engine

M47 M57 M67

Four, six and eight cylinder turbo diesels

1999 - 2006

BMW s50 engine

S54

Six cylinder 24 valve

1992 - 2007

 

BMW engines don't like the cooling system being neglected, you need a fluid change every 2 years at least. You'll hear a lot of stories about the cooling system being fragile but I'm not so sure. A lot seem to come from US owners and I wonder if the higher temperatures over there play a part.

If you buy an E36 change the spark plugs and run some Redex / Techron through the fuel system for best results. Also inspect the serpentine belt for wear.

Overheating in traffic is often due to a failing viscous fan coupling on early cars. Beware as it's reverse thread. From 2002 all cars had electric fans instead.

The N42 was highly innovative but seems prone to oil and vacuum leaks. It can sometimes have timing chain problems but it's not that common. Personally I'd avoid it and get a six cylinder.

The diesels are great if looked after. Ignored they will build up soot and run dreadfully, under 25mpg (Imperial) average isn't unknown. If sooty the whole intake tract needs to be cleaned out.

The diesels have swirl flaps to aid faster warming of the engine, these could be electrically or vacuum operated depending on age. The early ones have overly thin shafts which can break and let the flap fall into the cylinder - new engine time. They're easy to remove, see www.swirlflaps.co.uk

 

BMW E46 swirl flap

Diesel swirl flap about to fall into cylinder.

In order to meet stricter emissions laws these cars have oil separator units instead of the old PCV (Positive Crankcase Ventilation) systems. In a cold climate or with lots of short journeys these can clog leading to high oil consumption. Replacements parts including feed hoses are around 90 GBP but access on the M54 is poor.

If your car won't start it might be the electronic MAP thermostat. Mine died by shorting out, this killed fuse three in the little five fuse electronics box hidden in the engine bay. The fuel pump lives on the same fuse. Not an uncommon issue I believe. You can temporarily fix it by unplugging the thermostat and replacing the fuse, it'll drive perfectly but may run slightly hotter.

Transmission and Drivetrain

An odd knocking under acceleration or cornering could be the driveshaft centre bearing.

If you buy an auto gearbox and don't know when the fluid was changed last get it done along with the filter. This should be done every 60k miles, despite BMW's official line it's not lifetime fluid. If you have any issues with an auto gearbox a fluid change is the first line of attack. Same goes for the differential and power steering.

The SSG and SMG gearboxes aren't unreliable but can be very expensive to fix if they fail. Best to stick to a normal manual.

The transfer boxes on the four wheel drive cars can suffer from a failing electric motor. It's very easy to replace and costs about 300 GBP.

 

BMW E46 330i

330i with front off for better access, a little extreme.

Brakes, Suspension and Steering

The biggest issue with brakes by now is sticking calipers just through age. I do one or two a year on my small fleet of cars as the rubber boots perish and let dirt into the piston, it's worse for me due to the winters where I live. Refurbished calipers aren't expensive or hard to fit.

An ABS fault can be water in the connector for the sensor that lives about 18" from each sensor down the cable.

Good brake pads are worth the money, look for Pagid Fast Road or EBC Red Stuff.

Change the brake fluid when you buy the car then every two years. It's hydroscopic and gathers water, not a good thing.

 

BMW E46 control arm

Worn lower control arm bushings can cause poor handling and vibration.

Vibration when braking from speed is often due to worn lower control arm bushings. Replace with a poly bushing for best effect. Failing that check the tie rods.

If the car doesn't seem to handle in a stable way get a four wheel alignment. My E36 was hit from behind at about 15mph and suffered almost no damage. But it put the rear axle out of alignment and it drove horribly.

If laying the car up be sure to leave the handbrake off or it'll stick on.

If your steering is stiff or the pump groans when cold you need to change the power steering fluid. Sadly the reservoirs no longer have a removable filter.

Rear shock mounts often go at 40-60K. This shows up as a rattle when going over pot holes, not expensive to fix.

Interior

Be sure you'll fit! I'm 5'6" and need the driver's seat all the way forwards to reach the pedals. This means the steering wheel is too close even when all the way back.

If the fan seems to blow little air it might be due to a blocked microfilter. Very easy to change on this model, it's in front of the windscreen and just held by two plastic screws.

 

BMW E46 hedgehog

The "hedgehog" fan controller gets the name from it's heatsink. .

The blower fan can suffer from speed fluctuations especially at low speed due to a failing "hedgehog" controller. It's not bad to change and I must do it on mine, it's had the same fault for over two years!

If you have an airbag warning light get a code reader / reset tool, they're cheap. It's often the passenger seat occupancy sensor, you can buy a dongle to bypass it and then clear the fault code. In an accident all the airbags will deploy even if there's no passenger. An airbag warning light is an MoT failure.

Both interior and exterior door handles could have been of slightly higher quality. If they fail to open the door it's generally possible to fix things with a bit of fettling and bending of link rods. The bolt which holds the outside handle mechanism in place can slacken causing poor operation.

If you have the BM54 satnav with the full screen it can suffer a few problems including audio distortion. Best described (and remedied) here.

The six pack CD players can fail. Quite a few manufacturers used the same model but with a variety of wiring connectors. Not expensive on ebay.