Toyota RAV4 Forums banner

1 - 3 of 3 Posts

·
Registered
Joined
·
48 Posts
Discussion Starter #1 (Edited)
3rd Gen (2.5L) AFR/O2 Replacement

Our 3rd Gen RAV4 threw up the CEL, TRAC OFF, and 4WD lamps this winter. What the heck could that be?


Some quick work with the code reader and ended up getting the P0138 OBD fault code around 90,000 miles. Did some reading, checks, and ordered some AFR/O2 sensors to replace the originals. It is thought that the OEM exhaust sensors have a realistic lifespan of around 90,000 - 100,000 miles go figure.

Something worth mentioning. P0138 is generically described as an O2 Circuit Voltage High - Bank 1 Sensor 2. Which is truthfully indicating the rear O2 sensor has a problem. But......the actual failed part is likely not the rear sensor. In fact there are numerous posts that replacing the rear O2 sensor did not clear the fault code. The root cause is a faulty front AFR sensor which leads to an operation condition that the OBD system detects as a problem on the rear O2 sensor diagnostic. Confusing much?


You will need the correct parts first. I learned that there are some choices for the rear sensors. Do not start the job unless you confirm you have the correct parts. Visually check the new parts beside your existing parts before you really tear into the job.
Our RAV4's VIN starts with 2. So that's the application I'm looking for.
Japan built (J = 1st VIN character)
USA built (2 = 1st VIN character) Actually USA built is really Canada built.

Front Air Fuel Ratio (AFR) Sensor - Bank 1 Sensor 1
USA and Japan built RAV4 use the same sensor Toyota p/n 89467-42120 which is manufactured by Denso.
Denso (aftermarket) AFR sensor p/n 234-9022.

Rear Heated Oxygen (O2) Sensor - Bank 1 Sensor 2
USA built uses Toyota p/n 89465-0R010 which is manufactured by Denso.
Denso (aftermarket) O2 sensor p/n 234-4556.

Japan built uses Toyota p/n ??? - have not found it yet

Denso (afgermarket) O2 sensor p/n 234-4622.


You should also have any special procedures and any torque specs handy before starting the work. The field service manual (FSM) is the best place to get the most updated info. I highly recommend reading through the FSM first. The SIR regulations ensure you access to this information. Although you might have to pay for access.


Front AFR:
A)AFR sensor 44 N-m (32 ft-lbf) w/o Special Service Tool
B)exh manifold heat shield bolts xxxxxTBDxxxxx

Rear O2: Same specs were listed for both O2 sensor p/n's.
A)O2 sensor 40 N-m (30 ft-lbf)


Remember this is how I performed this work on my RAV4. The FSM is the best place to get these procedures. Duplicate my efforts at your own risk. However all you need is a bit of common sense or at least a friend willing to work for beverage.
 

·
Registered
Joined
·
48 Posts
Discussion Starter #2
Front AFR replacement - honestly this job is a cakewalk.

Tools you will need and some suggested:
-ramp, floor jack, jack stands, wheel chocks
-12mm socket with ratchet
-22mm box end wrench
-torque wrench (xx ft-lbs through 32 ft-lbs)
-hand torch - in case the threads are locked up
-OBD code reader with clear fault feature

Consumables:
-new front AFR sensor for your application
-anti-seize for sensor threads

Let's get this thing up were we can work on it. I used ramps since the entire front end needs to come up. But you can accomplish the same with a floor jack and safe placement of jack stands. Open up the hood because that's where the magic happens.


Pull off the top engine beauty cover. It just lifts off once the tension clips let loose. Then there are 4 bolts that hold the exh manifold heat shield in place. Two are right on top. The other two are further in the engine bay (red arrows) and might need some creative tools to remove.


The exh manifold shield will lift out as long as you start with the left corner (as you are facing it) first.


Here is your working area. The AFR bung and harness connector (red arrows) specifically. I go after the harness connection first since I prefer to use box end wrenches on exh sensors. As long as the harness connector can pass through the box end.


I found that removing this plastic bracket helps gain access to the connector. A small flat screwdriver helps lift the lock out of the way. Then just remove the bracket from the coolant hose and set aside.


The AFR sensor lead is held in place with this other coolant hose bracket. Pinching the locks allows you to open the bracket, pull it off the smaller hose, then set aside.


At this point you will have plenty of access to the harness connector. Remove the tab that holds the connector to the steel bracket. Then press down the connector lock and carefully pull apart.


If you lift the sensor lead upwards you can now slip the 22mm box end over the connector and engage the sensor body. Loosen the sensor body from the exhaust manifold bung. Once it is loosened you can take away the box end wrench and finish removing the AFR by hand.


At this point I always compare the original part to the replacement part. If it checks out OK then put a little anti-seize on the sensor threads. Just enough for the threads. NOT on the sensor probe.
*In this case the Denso aftermarket sensor lead is slightly longer (not a problem), the same harness connector body, and has a harness clip installed (easily removed).


Reinstall the opposite order of removal. The torque spec in this case (w/o SST) is 30 ft-lbf which I just end up going by feel on the wrench. Reconnect the harness connectors. Make sure to replace the brackets you removed earlier.


Reinstall the exh shield torquing the bolts to xxx ft-lbs then replace the engine cover.


Go get your code reader. Key ON but do not start the engine, use the reader to clear the fault code. If you do not have a code reader you can drive the car until the failed monitor passes and eventually clears out the fault code by itself.
*In my case this front AFR did remove the P0138 code on our RAV4. I ended up going after the rear O2 sensor a month later or so.
 

·
Registered
Joined
·
48 Posts
Discussion Starter #3
Rear O2 replacement - this job is a real PITA due to the confined space the sensor and harness connector are located. It was not my favorite but I wanted to switch the exh sensors out around the same time frame.
I will work on this one later. I did the job at night and it was hard to photo while working. I'll have to go back for better photos.

Tools you will need and some suggested:
-ramp, floor jack, jack stands, wheel chocks
-22mm box end wrench
-torque wrench (30 ft-lbs through 32 ft-lbs)
-hand torch - in case the threads are locked up

Consumables:
-new rear O2 sensor for your application
-anti-seize for sensor threads
 
1 - 3 of 3 Posts
Top