3 Series 1999 – 2005 (E46)
Ignition
Coils
These vehicles have exhibited an unusually
high failure of ignition coils. There is one coil for each
cylinder, located above the spark plug. The symptom is a misfire and
setting the “Service Engine Soon” warning. When we read out the fault
codes, we see “Misfire on cylinder X”. They seem to exhibit the
symptom most frequently after the engine is fully
warm.
Window
Regulators
We have seen quite a few failures of
these. Several
customers have reported having one or more replaced under
warranty. We have
replaced regulators in as many as three of the four doors in one
visit. If the window stops moving or begins to make quite a bit of
noise, do not continue to try to move it or the drive motor may also
be damaged.
Sun
Roof
The sun shade begins to not move in
synchronization with the roof
panel.
Front Thrust
Arm Bushings
This is a normal wear item in BMWs. These are somewhat more
expensive, as the bushing and its mounting are replaced as a unit,
unlike most of the other cars.
Lower Front
Wheel Well Liners
The forward section of the front wheel well is easily damaged
by road debris or bumping the concrete wheel stops in parking lots.
Fortunately it is inexpensive and easily replaced.
PCV
Valve
The vacuum valve on these cars has a higher
failure rate than the one on the previous 3 Series. Its failure
causes rough idling and sets the Service Engine Soon light. If your engine starts to
make a honking noise, like a small goose, this valve is the
culprit.
Cam Position
Sensor
The position sensor for the camshaft will go open, either
intermittently or completely.
If it fails completely, the engine won’t run. If intermittent, it will
die, then restart, run for a while, and repeat the cycle. It usually sets the “Service
Engine Soon” warning.
Thermostat
The thermostat on these engines is electronically controlled
and experiences a moderate failure rate. If it sticks open, the
engine doesn’t fully get to operating temperature. If it sticks shut, the
temperature rises rapidly and the vehicle needs to be stopped as
soon as safely possible, then towed in for repair. It may also be a
temporary failure, but should be replaced as soon as possible. These problems set the
“Service Engine Soon” warning.
Drive Belt Rollers
The idler and tensioner rollers for the main and A/C belts
seem to have a shorter service life than the other vehicles, even
though some of the components are used on other engines. When they begin to fail, the
bearings in these rollers make quite a bit of noise, particularly
when the engine is cold.
We recommend replacing all three rollers, one (or two) of
which is integrated with the tensioner, if problems occur, rather
than paying for the labor three times. If the belts aren’t new,
these should also be replaced, as no labor is involved
Differential Mount
Bushing
The bushing cracks, particularly on manual
transmission cars. If this is ignored, the rear subframe
mounts in the body may rip out, requiring an expensive trip to
the body shop.
Power Steering
Pump
There is a moderate occurance of power steering
pump failures. The shaft will break internally inside the
pump.
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