Parts and Tools for Oxygen Sensor Repair

Here are the parts and tools I needed for the repair:

(1) Denso (PN#234-4169) "first time fit" oxygen sensors with prewired electrical connectors. Quantity:2. $194 total, $97 per oxygen sensor, from www.oxygensensors.com, including shipping and handling. I was pleased with their promptness. After placing my order, I received my two oxygen sensors in 3 days.

(2) 22mm Oxygen Sensor Socket, 3/8" drive for bank 2, sensor 1 removal.

(3) 22mm crowfoot wrench socket, 3/8" drive for bank 1, sensor 1 removal. Note: I could have also used the crowfoot for bank 2, sensor 1.

Engine Under Cover Removal

Reference: Lexus 2000 Repair manual.

The pre-catalytic oxygen sensors can be reached after removing the engine under cover.

The engine under cover consists of two sections as shown in the picture. I remove both engine under cover panels. Removing 8 few hex bolts allows the engine under cover panel to be dropped.

I had plenty of clearance to work under the car and did not have to put the car on jackstands.

Oxygen Sensor Locations

The Lexus LX470 has a total of four oxygen sensors:

Bank 1 Sensor 1 (left exhaust manifold before catalytic converter)

Bank 1 Sensor 2 (left exhaust manifold after catalytic converter)

Bank 2 Sensor 1 (right exhaust manifold before catalytic converter)

Bank 2 Sensor 2 (right exhaust manifold after catalytic converter)

The two "Sensor 2" pre-catalytic oxygen sensors are subject to hotter and harsher exhaust gasses. They are the ones that fail first and the ones I need to replace.

My OBD2 reader reported an diagnostic trouble code (DTC) of P0155 or "O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)". However, it only makes sense to replace Bank 1 Sensor 1 as well since both are likely to fail near the same time.

Bank 1, Sensor 1 Left-bank Pre-catalytic Oxygen (O2) Sensor

After dropping the engine under cover, I unplugged the electrical connector of the left-bank pre-catalytic ( bank 1, sensor 1) oxygen sensor and unbolted the oxygen sensor with my 22mm crowfoot wrench socket with extension (see inset). Then, installed my new Denso oxygen sensor. One down, one to go.

Bank 2, Sensor 1 Left-Bank Pre-catalytic Oxygen (O2) Sensor

Removal and installation of the bank 2, sensor 1 oxygen sensor is straightforward with my 22mm oxygen sensor socket.