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BMW E39 Oxygen Sensor Replacement
 
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Pelican Technical Article:

BMW E39 Oxygen Sensor Replacement

Kerry Jonsson

Time:

2 hours2 hrs

Tab:

$300

Talent:

****

Tools:

22mm wrench or special oxygen sensor socket, 10mm socket with ratchet or wrench

Applicable Models:

BMW E39 5-Series (1997-98)

Parts Required:

Oxygen sensors

Hot Tip:

If reusing old O2 sensors do not use penetrating oil with silicone in it

Performance Gain:

Fixes failed oxygen sensor codes

Complementary Modification:

Change catalytic converters

Feedback fuel injection systems have been around since 1976. The oxygen sensors are mounted in the exhaust stream. It converts the oxygen content into an electrical signal the computer can understand. The oxygen content changes in the exhaust when the air/fuel mixture is either rich or lean. If the mixture is rich the computer makes it lean, and when it is too lean the computer responds by making it rich. This feedback improves fuel economy and reduces emissions. The computer monitors the oxygen sensors to make sure they are working properly and if they are not the computer will flag a code. In this tech article we are going to go over all the steps to replace the oxygen sensors on your E39

If you are going to use penetrating oil to help loosen the sensor make sure it does not have silicone in it. Silicone interferes with the chemical reaction that generates the electrical signal to the computer. Also you may need to heat up the "bung" (the piece welded to the exhaust that the sensor threads into) to loosen the oxygen sensor.

This photo illustrates under the right side looking up at the middle of the car.
Figure 1

This photo illustrates under the right side looking up at the middle of the car. We see two oxygen sensors (green arrows) that give the oxygen content before and after the catalytic converter. There are two more just like these two mounted in the left side exhaust pipe.

This photo illustrates under the left side of and E39 with a 6-cylinder looking underneath the middle of it.
Figure 2

This photo illustrates under the left side of and E39 with a 6-cylinder looking underneath the middle of it. Locate the black cover (green arrow) that houses the rear O2 sensor connectors.

This photo illustrates the left side about the middle of the car.
Figure 3

This photo illustrates the left side about the middle of the car. Locate the black cover (green arrow) that houses the oxygen sensor connectors on the 8-cylinder E39.

Remove the two 10mm plastic fasteners that hold the oxygen sensor connector housing to the body of the car.
Figure 4

Remove the two 10mm plastic fasteners that hold the oxygen sensor connector housing to the body of the car.

Remove the oxygen sensor wiring harness from the connector clips that attach the wiring to the heat shield.
Figure 5

Remove the oxygen sensor wiring harness from the connector clips that attach the wiring to the heat shield.

Flip over the connector housing and pull out the two electrical connectors (green arrows), one for each oxygen sensor.
Figure 6

Flip over the connector housing and pull out the two electrical connectors (green arrows), one for each oxygen sensor.

Squeeze the end of the electrical connector (green arrow) with one hand and with the other squeeze the body side of the electrical connector (yellow arrow) and pull the connectors straight apart.
Figure 7

Squeeze the end of the electrical connector (green arrow) with one hand and with the other squeeze the body side of the electrical connector (yellow arrow) and pull the connectors straight apart.

With a 22mm wrench loosen the oxygen sensor in the housing.
Figure 8

With a 22mm wrench loosen the oxygen sensor in the housing. The sensor may be on there pretty tight. You may need to apply heat to loosen it. You should use a special oxygen sensor wrench or socket to allow you to put it around the oxygen sensor and get past the wiring harness.

Working underneath the front of a 6-cylinder E39 chassis where the exhaust manifold meets the downpipe install a 22mm wrench or O2 sensor socket and remove the two O2 sensors (green arrows), both mounted in their own exhaust manifold.
Figure 9

Working underneath the front of a 6-cylinder E39 chassis where the exhaust manifold meets the downpipe install a 22mm wrench or O2 sensor socket and remove the two O2 sensors (green arrows), both mounted in their own exhaust manifold. Remember the first three cylinders make up bank 1 and cylinders 4 through 6 make up bank 2.

This photo illustrates underneath the middle of an E39 with the 6 cylinder just after the catalytic converter.
Figure 10

This photo illustrates underneath the middle of an E39 with the 6 cylinder just after the catalytic converter. Use a 22mm wrench or O2 sensor socket to remove the two post catalytic converter O2 sensors (green arrows)

When installing either the old or new oxygen sensors apply copper paste to the threads of the sensor before threading in the sensor by hand.
Figure 11

When installing either the old or new oxygen sensors apply copper paste to the threads of the sensor before threading in the sensor by hand. This will make later replacement easier. Installation is the reverse of the removal steps. Thread in the new sensor and tighten it. Plug in the electrical connector and pop it in the cover. Mount the cover and tighten the mounting nuts. Route all wiring the way you found it and clip it using the harness clips so the wiring is held tight to the body. Clear any codes that might have set.

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Comments and Suggestions:
Chris Comments: Hello, I'm getting an indication that the bank 1, pre-cat o2 sensor is offline. I replaced it with a proper Bosch sensor yet am getting same codes. I suspect that there is loose/broken connection in the male connector that the o2 sensor plugs into. When I tap it/shake it, there is feeling of something rattling free as opposed to the other pre-cat sensor which feels like a solid/one piece part. Do you have just that male end connector I think it is also made by Bosch and the numbers I see on it 09-3304 O2? My thought is to cut that connector off and crimp/solder to a new one and reconnect.
November 12, 2016
  Followup from the Pelican Staff: You will have to buy wires with terminals and a connector end.
Give The Pelican Parts parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.


To be sure of your diagnosis, run temporary wires to the DME connector to see if the issue goes away. Then you can have confidence in repairing the connector. - Nick at Pelican Parts
 
Mike Comments: Hi, do you have a tech article for a 2003 e39 540i with a M62 TU engine O2 sensor replacement?

Thanks
September 15, 2016
  Followup from the Pelican Staff: Only what is on this page.

We don't currently have that tech article. If we get a chance to perform the procedure, we will be sure to document it.

I would grab a repair manual. It will have the procedure, special tools and torque specs.

Give our parts specialists a call at 1-888-280-7799. - Nick at Pelican Parts
 

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Page last updated: Wed 12/7/2016 02:06:24 AM