Article by: RobRed

Applicable Models: 1998-2007 / 100 Series Land Cruiser or LX470

Last updated: April 17, 2019 at 11:05 am

The Land Cruiser 100 Series and LX 470 have 4 exhaust sensors, commonly referred to as “O2” sensors. Two of the sensors are “upstream” of the catalytic converters mounted into the exhaust manifolds. The other two are “downstream”, just past the bulge in the catalytic converters themselves. Commonly the upstream sensors fail at some point well into the Land Cruisers life presenting a Malfunction Indicator Lamp (MIL) and an associated OBD II code. In the Field Service Manual (FSM) the locations are referred to as Bank 1 (drivers or LH side) and Bank 2 (passenger or RH side). Sensor 1 is the upstream sensor and sensor 2 is the downstream  sensor.

Later model (2006+) refer to the downstream sensors as Air Fuel sensors. To complicate things more, Toyota calls for 4 different part numbers for each of the four sensors. Interestingly Denso only shows 2 part numbers, with no difference for left or right.

Below is a grid of part numbers. You should verify these part numbers with Toyota or Denso before ordering.

 

 

Changing these sensors is no big deal for the do-it-yourself mechanic. The process requires the removal of the composite belly pan for the upstream sensors, so you can access the motor from underneath. Additionally having either a oxygen sensor “tool” or a 23mm flex head ratcheting wrench will make life very easier for the upstreams. The downstream sensors are held in place by two 12mm nuts at each one.

Before you begin any modification to your vehicle you should fully understand what you are doing and make sure you have the skills to complete the job. TLCFAQ nor it’s authors, commentors or contributors accept any responsibility, or liability for any mishap or problems from any materials posted on the website. Any and all of this can cause serious damage to you or your vehicle. Always consult a qualified professional. I’m Serious. Do this at your own risk.

Front / Upstream Sensors:

1. Make sure your Land Cruiser is in gear, parking brake set and wheels chocked.
2. You are working on exhaust components! Make sure the truck is sufficiently cooled down before beginning this.
3. Remove the belly pan. Optionally for the RH/passenger side some folks remove the passenger front wheel and pop the fender liner open to access the RH sensor. It’s tight in there.
4. Locate the first sensor and follow the wiring back to the engine bay until you find the sensor connector. It’s about 8″ from the sensor to the connector.
5. Unplug the connector. this may require a soft pry tool to press down on the connector release if they are stuck.
6. Pull the wiring down from the clips that keep it out of harms way.
7. Thread the wiring through the sensor tool or ratcheting wrench and seat the wrench on the sensor.
8. Apply counterclockwise force to loosen the sensor from the manifold.
9. Remove the old sensor and thread in the new unit by hand then tighten to spec with your sensor tool or wrench. I recommend some high-temp anti-seize on the threads CAREFUL not to get the anti seize on the sensor itself. The Denso sensors come with anti-seize in the package.
10. Reverse the order above and repeat for the other side.

 

 

Rear / Downstream Sensors:

1. 1. Make sure your Land Cruiser is in gear, parking brake set and wheels chocked.
   2. You are working on exhaust components! Make sure the truck is sufficiently cooled down before beginning this.
   3. Locate the catalytic converter and the sensor is located aft on the top of the tube.
   4. Locate the first sensor and follow the wires back to the main harness above until you find the sensor connector. It’s about 8″ from the sensor to the connector.
   5. Unplug the connector. this may require a soft pry tool to press down on the connector release if they are stuck.
   6. Pull the wiring down from the clips that keep it out of harms way.
   7. Thread the wiring through the sensor tool or ratcheting wrench and seat the wrench on the sensor.
   8. Apply counterclockwise force to loosen the sensor from the manifold.
   9. Remove the old sensor and thread in the new unit by hand then tighten to spec with your sensor tool or wrench. I recommend some high-temp anti-seize on the threads CAREFUL not to get the anti seize on the sensor itself. The Denso sensors come with anti-seize in the package.
   10. Reverse the order above and repeat for the other side.