I own an '06 IS350 and had my CEL, VSC and Trac lights come on last week and I got the codes read with the outcome of P0031: Oxygen sensor heater (bank 1, sensor 1) and C1201: Engine control unit.

I've spent hours looking for images to assist which sensor this is for and I'm struggling a bit to nail it down. I come across some which show it's underneath the car and closer the front, and then others that show it's underneath but closer to the firewall. Can someone please enlighten me here a bit as I'm a bit stuck and would love to get this sorted. The other thing I'm wondering is with this code whether it's the right thing to do to replace the whole cable (going to cost me around $470 OEM in New Zealand), or if it's just a smaller part of it that can be done for cheaper?

Thanks in advance!

 

Facing the engine down below the brake booster. You can't miss it. It has 4 wires Blue, White, Black... ETC it's on the bronze exhaust manifold near the fire wall.

Then again your in the Land Down Under. I'm not sure which side your break booster is on.

 

Bank 1 in the US is the passenger side. So on the other side of the world, is it the same side? IDK. But once you figure that out, sensor 1 is the upstream or FIRST sensor actually within the factory exhaust manifold. Replace that O2 sensor AND consider doing both or buying two. The replacement sensor will fix those CELs.

 

Is that first o2 sensor accessible from underneath the battery tray? Or do you have to get to it from underneath the car?

 

The easiest way is from underneath the car.

 

Just keep in mind that B1S1 is before the CAT but part of the exhaust manifold.
B1S2 is after the first CAT (assuming one has the OEM exhaust manifold w/CAT).

Cylinders:
Bank 1 has cylinders 1, 3, 5 from front to back RS of car.
Bank 2 has 2, 4, 6 LS of car.

 

Thanks for the info guys! I'm pretty comfortable with what to do now so I'll go ahead and get the part ordered.

The guys at my local auto parts store are quoting me $470 for an OEM sensor, but I go online and see all of these https://nz.dhgate.com/toyota-oxygen-...w-zealand.html How do I know which one is the right one?

 

The US part # for the replacement upstream Denso O2 sensor is : 234-9051. I got this using Ebay.