K1200LT Oxygen sensor r/r

Author: Stefan

Since I did this somewhat different from the procedure listed in the manual, below are the steps and related information. It took me about 30 minutes in total.

Background: My LT has not, in my opinion, run at par for the last couple of years. Not that there has been a big difference, but my fuel mileage has not been what it used to be and, to me, it has smoked more than it should at hard acceleration.

I have taken it to the BMW dealer twice for a diagnose and both times no errors have showed up for the O2 sensor and not for anything else for that matter. Both times the charge was 50 euros just for the hook-up.

At the last ride, the O2 sensor definitely bailed out and it was a fairly easy diagnose, without the dealer. Although it could have been a vacuum leak as well, hence the tip for diagnostic wiring harness later.

Fuel mileage dropped to below 30 MPG at normal riding and it has a tough time idling after reaching operating temperature. In addition, the engine “rattled and clunked” more than usual. However, the Motronic did a real good job “masking” it.

At the end of this, there is a tip on how to make a diagnostic harness, that eliminates the need of having a dealer perform a diagnose of the O2 sensor.

The LT O2 sensor is the same as in the car BMW 540i and manufactured by Bosch. It pays to find this part from a different source. Personally I got mine from non-BMW source at 70 euros, including shipping to France. That is about 100 euros less than the dealer.

The Bosch part number is 0 258 003 475

The number defines a part that has the correct length cable and connector. Do not use another part number, unless you are prepared to do your own connections.

To do the job, the following items besides the regular Torx T-25 and 6 mm Allen wrenches are needed:

22 mm wrench, an Oklahoma metric (crescent wrench) works well too. The hexagon nut is big and easy to reach.

2’ feet of string up to ¼” thickness

5 wire ties/zip ties

A little bit of grease to lube the shift linkage at the end, since you are in there anyway.

I would also recommend replacing the spark plugs, or at least get them cleaned since they are most likely covered in sot resulting from an incorrect fuel mixture. I replaced mine with NGK Iridium DCPR7EIX at 19.00 euros at the local French auto parts store and $8.49 at NAPA. Go figure

Removal procedure:

  1. Remove left passenger foot rest
  2. Remove left side cover
  3. Remove left rider foot rest, including disconnecting the shift linkage.
    I usually mange to release the little clip that locks onto the shifter ball with my finger. If you can’t, use a screwdriver or something else.
    Once the clip is released, lift it up and remove it.
  4. Carefully release the shifter ball from the shift linkage socket.

Note: Once you have this removed, take a look at how it is all set up before you start the removal of the O2 sensor.

If you want to make the diagnostic harness later, don’t just cut the connector from the cable to/from the currently installed O2 sensor to ease the removal.

Look at the top of the exhaust system, you will see the O2 sensor standing right up, with a fairly thick “cable” routed upwards through a plastic clip.
Open this clip and release the cable.

Looking directly from the top at the connector area, the connector is the 3rd one down and fairly long and narrow. Compare it to the connector on the new sensor if you are not sure.

This cable is secured (together with two other cables) with a wire tie that is looped through a plastic plug. Be careful when you cut it/remove it so you don’t damage the plug because you’ll use it again. Also ensure you note how the other two cables are folded in the wire tie.

  1. Pull the connector out of the clip and separate the two connectors

Tip: Get the string and one wire tie. Attach the string to the cable/connector of the old O2 sensor. You want the string to come out under the bike and still have the end of it accessible from the top. You want to use this string when you pull up the cable for the new O2 sensor.

  1. From under the bike, start pulling the cable out ensuring that the string does not come off the cable. Pull the cable end completely out so it is free from all brackets, etc. and release the string. If you do this right, there will be no questions after, like “Oh shit, how was this routed? Did it go through the bracket or outside of the bracket?”
  1. Get the 22 mm wrench or a crescent wrench and break loose the O2 sensor. It may take a bit of torque or a swift hit with a rubber mallet on the wrench handle to break it loose. Once it is done, you can turn it by hand.
  1. The new O2 sensor already have “Never seez compound” on its threads and it is ready to install. Do the initial threading by hand and make sure you do not cross thread. You have to turn the cable once in a while when you turn the O2 sensor.

Note: The tightening torque of the O2 sensor is 45 Nm. I did not have the correct tools for this, but tightened it to what I felt comfortable with. If you don’t have a torque wrench that’ll work for this and is not used to the feel of 45 Nm, be careful not to over torque and strip the threads.

  1. To route the cable back up, I used 3 zip ties to secure the string to the new connector. I clipped on directly at the cable below the connector. One along the side of the connector and the 3rd zip tie I looped through the two holes by the opening of the connector.
    I routed the string under this last zip tie to get it in the center of the clip to have the pulling “force” right there. It is easier to pull a “straight” connector through than one that is side ways, like it would be with e.g. a clip at the bottom of the connector.
  1. If you pulled the string completely out and did not release it from the connector before, you can just start to pull on the string from the top as you assist and guide it with the other hand from the bottom. It is real easy.
  1. When you have it completely out at the top, attach the cable to the plastic clip right above the shift linkage on the frame. You have to do this from under the bike.
  1. Clip the wire ties and release the string.
  1. Connect the O2 connector to the male end from the harness.

Note: I usually do not apply any die-electric grease or other compound to the O2 connector. It is weather proof and I don’t want to have anything there that may remotely interfere with the connection.

  1. Get the last wire tie and loop it through the plastic clip. Fold the other two cable as they were before and together with the O2 cable, zip it up enough so they stay in place. Don’t over tighten it.

Tip: Since you have free access to the shift linkage, it is easy to lube it up before you put the shifter and the foot rest back together.

The rest of the process is reverse from how you took it apart.

The torque to secure the foot rest bolts is 21 Nm

Diagnostic wiring harness: Don’t just throw away the old O2 sensor. Cut the cable about 4-5” after the connector. If you have a chance to salvage a male harness connector from another LT, or get it from another source – get it. With it you can easily make a real nifty diagnostic tool that does not require a trip to the dealer for diagnosing a faulty O2 sensor. If you locate the signal wire and make a T-connection, it is easy to get it connected to a multi-meter and diagnose without having to peel the sheathing or pierce any wires. Just place the device between the two connectors, fire up the bike and you can do it without the help of BMW. If you get the O2 sensor from a regular part store, you just saved yourself enough money to go for a nice little trip.

In addition, you can do a test while riding the motorcycle, which may provide more information.

Test procedure using the diagnostic harness:

I use a Fluke 88 for this that has a min/max reading, but the procedure is the same for similar meters.

  1. Shut the engine off and connect the leads to a. ground and b. signal voltage wire
  2. Set the meter to volts dc
  3. Select a 4V range
  4. Start the engine. If the O2 sensor is unheated, let the bike idle for a few minutes. Then press MIN/MAX to select the recording
  5. Check the MAX reading
  6. Check the MIN reading
  7. Check the AVG (average) value. Depending on how the reading is taken, the values may vary some but usually average around 0.450 V.