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S54 Engine Oxygen Sensor Replacement
 
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Pelican Technical Article:

S54 Engine Oxygen Sensor Replacement

Nick Czerula

Time:

3 hours3 hrs

Tab:

$300

Talent:

****

Tools:

Oxygen sensor socket, 22mm wrench, flathead screwdriver

Applicable Models:

BMW E46 M3 Coupe/Conv (2006)
BMW Z4 Coupe/Conv (2006)

Parts Required:

Oxygen sensors, anti-seize paste

Hot Tip:

Work with a cool exhaust

Performance Gain:

Remedy fault codes and maintain proper running engine

Complementary Modification:

Replace in pairs

Oxygen sensors monitor the exhaust stream, comparing the oxygen content in it to the oxygen content ambient air. When oxygen content is low, sensor voltage is high, when oxygen content is high, sensor voltage is low. The voltage created by the sensor is sent to the DME (engine control module) to help maintain a proper fuel mixture. The mixture preparation is used to keep the catalytic converters running at peak efficiency. The oxygen sensors used in Z4M models covered in this article have four wires. Two of which are for oxygen sensor heating and two for the signal. The heater is used to get the sensor online faster. Previously, exhaust heat was used. One wire supplied a ground to the sensor for the signal, and the other is for the sensor signal.

Oxygen sensors should be replaced every 100,000 miles. In a perfect world that would be it. Wait until a specified mileage and replace the sensor. However, these sensors fail prematurely, set oxygen sensor fault codes and reduce fuel economy. In this article, I will show you how to identify the location of all four oxygen sensors and how to replace them. You will need an oxygen sensor socket to remove the sensors and remember to always work with a cool exhaust. Oxygen sensors are fragile. Do not drop, damage may occur. Also, keep the sensor tip clean when reinstalling.

Oxygen sensors are laid out in banks, which refer to cylinders and in sensor numbers referring to before or after the catalytic converter. Bank1 or B1 refers to cylinders 1-3. Bank 2 or B2 refers to cylinders 4-6. Sensor 1 or S1 refers to the sensor before the catalytic converter. Sensor 2 or S2 refers to the sensor after catalytic converter.

Remember your car may have been serviced before and parts replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Never work on your vehicle if you feel the task is beyond your ability.

Our vehicle may vary slightly from yours as models do change and evolve as they grow older. If something seems different, let us know and share your info to help other users. Questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

Oxygen sensors are laid out in banks, which refer to cylinders and in sensor numbers referring to before or after the catalytic converter.
Figure 1

Oxygen sensors are laid out in banks, which refer to cylinders and in sensor numbers referring to before or after the catalytic converter. Bank1 or B1 refers to cylinders 1-3. Bank 2 or B2 refers to cylinders 4-6. Sensor 1 or S1 refers to the sensor before the catalytic converter. Sensor 2 or S2 refers to the sensor after catalytic converter. Bank 1 Sensor 1, red arrow. Bank 2 Sensor 1, purple arrow.

Oxygen sensors are laid out in banks, which refer to cylinders and in sensor numbers referring to before or after the catalytic converter.
Figure 2

Oxygen sensors are laid out in banks, which refer to cylinders and in sensor numbers referring to before or after the catalytic converter. Bank1 or B1 refers to cylinders 1-3. Bank 2 or B2 refers to cylinders 4-6. Sensor 1 or S1 refers to the sensor before the catalytic converter. Sensor 2 or S2 refers to the sensor after catalytic converter. Bank 1 Sensor 2, red arrow. Bank 2 Sensor 2, purple arrow

Replacing sensors before catalytic converter: Oxygen sensors are located in the exhaust manifold.
Figure 3

Replacing sensors before catalytic converter: Oxygen sensors are located in the exhaust manifold. To make room to work, remove the secondary air pump and hoses, see our tech article on secondary components replacing. Start by removing the crankcase breather hose. Disconnect the electrical connector (inset) by pressing the wire release and pulling the connector straight off. Then lift the solenoid (green arrow) up and out of the mounting bracket. Next, detach the breather hoses from the intake and breather (red arrows).

To remove the breather hoses, squeeze the collar and pull straight up.
Figure 4

To remove the breather hoses, squeeze the collar and pull straight up.

Place breather hose and solenoid aside (green arrow).
Figure 5

Place breather hose and solenoid aside (green arrow). You can leave the rubber hose attached. It only has to be moved enough to make room for the engine cover to come out.

Remove the six 10mm engine cover fasteners (red arrows).
Figure 6

Remove the six 10mm engine cover fasteners (red arrows). Then remove the oil filler cap (green arrow).

Lift and remove the engine cover.
Figure 7

Lift and remove the engine cover.

Working at the rear corner of the cylinder head, pull the wiring harnesses (red arrows) out of the holders.
Figure 8

Working at the rear corner of the cylinder head, pull the wiring harnesses (red arrows) out of the holders.

Working at the rear corner of the cylinder head near the camshaft sensor (purple arrow), remove the 13mm heat shield fastener (red arrow).
Figure 9

Working at the rear corner of the cylinder head near the camshaft sensor (purple arrow), remove the 13mm heat shield fastener (red arrow).

Then, remove the three 10mm fasteners (purple arrows) then remove the secondary air check valve, remove the 13mm heat shield fasteners (red arrows).
Figure 10

Then, remove the three 10mm fasteners (purple arrows) then remove the secondary air check valve, remove the 13mm heat shield fasteners (red arrows).

Working at the rear corner of the cylinder head, pull the wiring harnesses (red arrow) out of the heat shield.
Figure 11

Working at the rear corner of the cylinder head, pull the wiring harnesses (red arrow) out of the heat shield.

Lift and remove the heat shield (red arrow).
Figure 12

Lift and remove the heat shield (red arrow).

Locate the oxygen sensor electrical connectors at the rear of the cylinder had.
Figure 13

Locate the oxygen sensor electrical connectors at the rear of the cylinder had. Label or mark the wiring harness to aide during reinstallation. I suggest replacing one sensor at a time so you do not mix up connectors. Bank 1 Sensor 1, red arrow. Bank 2 Sensor 1, purple arrow. Press the release tab and pull the electrical apart (inset).

B1S1: Using an oxygen sensor socket (red arrow), loosen the oxygen sensor connection to the exhaust manifold.
Figure 14

B1S1: Using an oxygen sensor socket (red arrow), loosen the oxygen sensor connection to the exhaust manifold. Do not unscrew yet. Pull the wiring harness out of the mounts along the valve cover.

Remove the oxygen sensor from the exhaust manifold.
Figure 15

Remove the oxygen sensor from the exhaust manifold. Lightly coat the new oxygen sensor thread with anti-seize compound. Install the new oxygen sensor and tighten. Then reroute the wiring harness and connect the electrical connector and install the heat shields. Repeat if replacing both sensors. Then reassemble the engine covers and clear any engine fault codes using a BMW scan tool.

B2S1: Using an oxygen sensor socket (red arrows), loosen the oxygen sensor connection to the exhaust manifold.
Figure 16

B2S1: Using an oxygen sensor socket (red arrows), loosen the oxygen sensor connection to the exhaust manifold. Do not unscrew yet. Pull the wiring harness out of the mounts along the valve cover. Remove the oxygen sensor from the exhaust manifold. Lightly coat the new oxygen sensor thread with anti-seize compound. Install the new oxygen sensor and tighten. Then reroute the wiring harness and connect the electrical connector and install the heat shields. Repeat if replacing both sensors. Then reassemble the engine covers and clear any engine fault codes using a BMW scan tool.

Replacing sensors after catalytic converter: Oxygen sensors are located in the exhaust, behind the catalytic converters.
Figure 17

Replacing sensors after catalytic converter: Oxygen sensors are located in the exhaust, behind the catalytic converters. First, disconnect the electrical connector of the oxygen sensor you are replacing. I suggest replacing one sensor at a time so you do not mix up connectors. Bank 1 Sensor 1, red arrow. Bank 2 Sensor 1, purple arrow.

Unclip and lift up the wiring harness housing.
Figure 18

Unclip and lift up the wiring harness housing. Squeeze the tabs (red arrows) and flip up. Then remove the electrical connector for the sensor you are replacing from the holder. Disconnect the electrical connector by pulling it straight apart (inset).

B2S2: Using an oxygen sensor socket with a universal adapter (red arrow), loosen the oxygen sensor.
Figure 19

B2S2: Using an oxygen sensor socket with a universal adapter (red arrow), loosen the oxygen sensor. Unscrew the sensor and remove from exhaust. When reinstalling the sensor, do not allow the harness to remain twisted. Be sure it is properly routed and tension free. Lightly coat the new oxygen sensor thread with anti-seize compound. Install the new oxygen sensor and tighten. Then reroute the wiring harness and connect the electrical connector. See following step if replacing both sensors. Then reassemble the engine covers and clear any engine fault codes using a BMW scan tool.

B1S2: Using an oxygen sensor socket (purple arrow), loosen the oxygen sensor.
Figure 20

B1S2: Using an oxygen sensor socket (purple arrow), loosen the oxygen sensor. Unscrew the sensor and remove from exhaust. When reinstalling the sensor, do not allow the harness to remain twisted. Be sure it is properly routed and tension free. Lightly coat the new oxygen sensor thread with anti-seize compound. Install the new oxygen sensor and tighten. Then reroute the wiring harness and connect the electrical connector. Repeat if replacing both sensors. Then reassemble the engine covers and clear any engine fault codes using a BMW scan tool.

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Page last updated: Wed 12/7/2016 03:03:22 AM