O2 sensor - Bank 2, Sensor 1 - Replacement

After replacing the faulty Bank 1, Sensor 1 sensor this week it made sense to replace the other Bank 2, Sensor 1 as they have both been in the car for the same period of time.

Bank 1 took 15 minutes to do - Bank 2 took 1 hour 30 minutes to do. Both are located in the engine bay - Bank 1, Sensor 1is on the drivers side (UK models) and Bank 2, Sensor 1 is on the passenger side (UK models).

Replacement of the Bank 1 sensor is in the IS250 general forum.

Bank 2 is shown below.

Take your time doing this one as there are a few parts to remove so be patient and do it right. Also - be careful not to drop anything through the engine on this side as it will not go straight through the engine bay to the floor as I found out with a screwdriver I dropped (shown in a picture). You can get dropped items out but its a bit of hassle doing so.

There are non engine covers to remove on this side.

Make sure the engine is cold. You will burn yourself if its hot !!

Remove the battery terminals using a size 10 mm socket drive. Then remove the securing bar which is also a 10 mm nut. Remove the nut then lift the bar out of its securing tab as shown in the picture below (Picture 1)

Next you will need to remove the frame that the battery sits in. This is a plastic formed frame - there is a connection that is secured onto the engine side of this frame that needs to be removed first before removing this from the battery. Once the connector is removed then the frame can be lifted out of the way - Picture below shows the location of the connector (picture 2)

Just a note - you cannot get to the sensor without removing these items - they need to come out to replace it. It cant be got to from under the car either so the only way is down !

Picture below is of the removed battery - Panasonic? - don't know if this is the original battery that Lexus installed? (picture 3)

The next picture shows the battery tray (battery removed) also shows the connector that you have removed from the battery housing - the "tray" that the battery sits on will just lift out of the way (not secured by anything) and once removed will reveal an electronic box you need to remove. While at this point it is wise to check a wiring "bung" indicated in the picture as I found when it rains that the rain passes this connection - just check for water tightness etc as the wiring from this leads into the cabin. (just thought I would check this while I had all the parts off the car) Picture below (Picture 4)

With the battery tray now removed this will now reveal the electronic box and 3 plugs that need to be removed from it along with 3 bolts that need to be removed to get the unit out. The picture below describes how to remove the securing connectors from the plugs. Quite a fiddly job so be patient. Once you have the small securing tabs lifted up (by approx. 5mm) then the connector levers can be lifted upwards and in turn this will pull the connectors most of the way out. Total removal will require you to pull out gently so they are fully removed. There are 3 bolts indicated in the picture that removes the unit from the tray. I removed the bolts first as it gave me a bit of "play" to move the box around while removing the plugs but the plugs can come out first (I don't think there is a specific way to do this) (Picture 5)

The picture below shows the unit removed after taking out the 3 bolts. (picture 6)

The next picture shows the securing bolts (3 of them) that you will need to remove to get access to the sensor. Be careful when removing the tray as you will need to move the disconnected wires out of the way while doing this. Also - before the tray can be fully removed, there is a wire secured to it which is a bit awkward to get to the securing clip. If you are careful you can gently lift the tray up and get to the securing tab. Just squeeze these together and the clip will come off the tray. Once this is off then the tray can be lifted out... (picture 7) (picture 8) and (picture 9)

Now you have the tray out the sensor can be fully visible - give it a good dose of WD40 - I found this sensor was quite tight and I used quite a bit of force (hammer and metal bar on the 22mm sensor socket) to get it loose enough to turn by hand. Careful if doing this. (3 to 4 whacks gave it up and it started to turn) the picture shows the sensor lead running to the socket. LOOSEN ONLY AT THIS POINT - You cannot see the sensor plug socket. (picture 10)

The picture below shows the sensor plug / socket. It is not visible and can only be removed by feel so knowing where and how the socket is attached is important. The socket is located between the engine and bulkhead - if you look at the length of wire on the new sensor you have then this will give you a good idea of the location of the plug. The removal tab on the socket is the same as the Bank 1 socket - it is facing the bulk head. There is enough room to get both your hands in to remove the socket. Press the tab and gently pull the plug and it will come away. Take the plug out first as in doing so it will be easier as if you do the sensor first then the wires will twist as there are quite a few turns involved to take the sensor itself out. Remove the sensor and replace with the new one - take it easy at this point, due to the space involved, you could drop or damage the sensor but if you take it easy then there will be no issue. After replacing the sensor then plug it into the socket. (picture 11 and 12)

The re-fitting is the opposite to removal.

After completing it - and with the engine on, you will see a bit of smoke which is normal as it is the WD40 burning off and also the copper slip. It will go after a while.

I hope this helps people doing the replacement - cost of both sensors was £150 (£200 if duty was applied), Denso sensors - 234-9051 - the sensors are the same for bank 1 and bank 2. Purchased from the USA.