BMW M5 Cam Position Sensor
Replacement
2000 M5 E39 Exhaust Sensor Bank B (Driver's Side)
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Service Engine Soon light ->
OBDII Code P0390
OBDII Code P0390 indicates failure of camshaft
position sensor for exhaust cam on bank B (Driver's
Side). This is a frequent failure on E39 540i and M5
V8 engines. Other symptoms include slight loss of power
accompanied with a deeper than usual 'blatty' exhaust
tone.
Buying a New Sensor
I ordered a new sensor from Rock Auto Parts for
$105. With Rock Auto, I've found great deals, the prices are good and
the shipping is fast. Unfortunately, this time they
sent the wrong sensor (intake instead of exhaust). I'll
let them know to change their description, and I'm sure
they will give me a credit for the part.
So, since I already had the old sensor
out, I bought the correct sensor from Allison BMW Dealership
in Mountain View California. They had six in stock,
so I'll guess that the sensor often fails. List price
was $127 and they gave me a 10% discount through BMW
CCA.
Not from the top
Some folks prefer to change these sensors from
the top. This was just too tight for me and I didn't'
want to remove air ducts and hoses to get to the sensor.
Instead, I jacked up the car and replaced the sensor
from underneath.
Necessary Tools
This is the easy part. You will need a large
Phillips screwdriver to remove and replace the plastic
plate under the transmission. You will need a 5mm hex
driver, and a small ratchet. Space is tight, so smaller
is better.
Drop the Plate
I jacked up the car on the left side (Driver's
side) and placed two jack stands for safety. Eight or
ten screws hold the plastic shield/plate in place. It
drops very easily.
Remove the shield by loosening
Replace the Sensor
Look up between the header and transmission and
you will find the sensor with a 5mm hex head holding
it in at the rear of the left cylinder head.
It is difficult to get a ratchet and
hex driver around the water hose, but I managed to drive
the hex bolt from both behind and in front of the hose.
Once you have the sensor out, wipe the
hole clean.
Be sure to use a new O-ring when putting
in the new sensor. You may want to put some thread lock
on the bold on reinstallation.
Don't forget to re-connect the electrical
connector.
Replace the plate, let down the car and
drive.
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