7tisix

07 IS350

ODBC code P0157.
Bank 2 sensor 2 is the "Downstream" sensor. Order DENSO Part # 234-4521.

Remove the top of the center console so you can unlatch the carpet so you can pull it down. No need to remove the seat, just position it as far back as it will go so the carpet will be easy to deal with. The connector for B2S2 O2 sensor is between the ash tray and the gas pedal.
I used Aerokroil a couple days before I changed the sensor and didn't have any trouble getting it loose using a cheater bar.

Don't buy a deep socket Oxygen sensor socket. It will not clear the unibody frame and you will need to bust the exhaust loose. Don't get a short one either, it won't reach the nut because it's in a heat shield. I found a socket at AutoZone that works perfectly.

mr2seater

Just wanted to say thanks for the guide! I did B2S1 and it was not fun at all. Cleared my P0051 and pending P2197. 170k on my 250 and I assume they haven't been touched before. I was able to get the plug from the top, it took me about 15 minutes just for the plug. I wish I could have found it for $64 like you, cheapest I could get the A/F sensor was $105 on Amazon. Still better than paying the dealer!

MlikShakes

Howdy,

Same thing as the poster above, wanted to thank you for the post, all though it was tricky without pictures the info was spot on!

DonMerdjan

Let me share my experience and I hope it helps someone:
I have '06 IS 250 RWD Manual Transmission. At the 130k miles mark the check engine light came on. After checking the codes, I was getting the following:

• P0051 - Heated oxygen sensor, heater control circuit low Bank 2 Sensor 1
• P2197 - Oxygen sensor signal biased / stuck lean Bank 2 Sensor 1
• P0158 - Oxygen sensor, circuit high voltage Bank 2 Sensor 2

After reading the forums I decided it was time to replace the sensors. I decided to replace all four sensors while I am at it and have a piece of mind.
First, it wasn't very clear where the Banks are so I did some more research and according to this official document:

• IS 250 2006-2010; IS250C 2010 are with Engine model number 4GR-FSE. First Cylinder is on the passenger side, therefore Bank 1 is on the passenger side; Bank 2 is on driver side!
• IS 350 2006-2010; IS350C 2020 are with Engine model number 2GR-FSE. Same as above
• IS F 2008-2010; has Engine model number 2UR-GSE. This is a V8 and First Cylinder is on Driver side, therefore Bank 1 is on driver side. Bank 2 is on passenger side.

Then came the part numbers. I used the official denso website http://densoautoparts.com/find-my-pa...#searchResults
From the website it became clear that the RWD uses the same sensor for both upstream sensor 1 on both banks; and the same downstream sensor 2 on both banks:

• Air Fuel Ratio Sensor /Upstream - for RWD part number is 234-9051 for both left and right
• Oxygen Sensor /Downstream - for RWD part number is 234-4521 for both left and right

If you have AWD though the sensors differ from left (Bank2) and right (Bank1)

• Air Fuel Ratio Sensor /Upstream Left, part number is 234-9051
• Air Fuel Ratio Sensor /Upstream Right, part number is 234-9058
• Oxygen Sensor /Downstream Left, part number is 234-4518
• Oxygen Sensor /Downstream Right, part number is 234-4521

I bought all the four sensors from Amazon but rockaouto.com had a comparable prices. The OEM Denso sensors do come with anti-seize lubricant which is important to apply.

I also bought this helpful tool set:
Replacing the sensors was tough. The toughest was getting to them and then getting them loose. Had to use a lot of WD40 to loosen the sensors, which later caused some smoke when the exhaust got hot but it eventually burned out.

Getting to the downstream sensors was easy once you lift the car. They connect inside the cabin and in my case I had to lift the carpet a little bit to reach the connectors. Connection was on the side of the stereo system. I did not have to take the whole seat out as some suggest.

Upstream Sensor Left, Bank 2 driver side - it was hard to get. Some suggest taking the steering column out and reach from inside the cabin but in my case I was more successful by unscrewing a little box (don't know what it is for) that was on the way, disconnecting what I could and moving to the side. Then I was able to reach the sensor with the tool, a ratchet and an extension arm of the ratchet. After some WD40 and patience I was able to unscrew the sensor. Disconnecting it was tough as I had to reach behind the engine.

Upstream Sensor Right, Bank 1 passenger side - also hard to get. I had to remove the battery and the ECU (be very careful because this is an expensive part to replace if you break anything). Then I was able to reach the sensor with the tool and a ratchet to loosen it after some WD40 and patience. Disconnecting it was not very hard.

My Engine Light is now off and I hope it won't come for another 100K miles.

Hope this helps.

Gville350

iTrader: (10)

Great info! Another two helpful tips if you're falling victim to rusted or difficult O2 sensors, PB Blaster and a torch.

5gears-IS

iTrader: (5)

I highly doubt that two sensors will go bad at the same time...

Met

Hey, I know I'm late to this thread, but did you ever manage to upload pictures describing the directions? Thanks