P0138 Bank 1 Sensor 2

[Tpatel]

P0138 alarm came up in my 1.3 Petrol Toyota Auris (59 plate). The diagnostics showed up the above code which points towards changing the oxygen sensor. The sensor was changed 3 times with various after market brands and after about 30 miles of driving the engine light would come back up. The sensor was then replaced with a OEM part and the light came on again after 30 miles. 
 

Every time the diagnostics is done it always shows the same code. If the sensor is changed what other part in the car could be causing this code?

[furtula]

You don't want to use aftermarket brands when it comes to replacing the 02 sensor. I had the sensor malfunction on my old car, went to a shop, they replaced the sensor with a used, but OEM part, and only 3rd time did it catch on, and the light stayed off.

Here's the troubleshooting manual for that code, you need to translate it to English. 

From what i see, it says to check the sensor with a multimeter to verify it's working, then check connections, and/or replace.

https://corolla-club.ru/doc2/rm04f1ru/repair2/html/frame_rm000000wby02fx.html

[Tpatel]

8 hours ago, furtula said:

You don't want to use aftermarket brands when it comes to replacing the 02 sensor. I had the sensor malfunction on my old car, went to a shop, they replaced the sensor with a used, but OEM part, and only 3rd time did it catch on, and the light stayed off.

Here's the troubleshooting manual for that code, you need to translate it to English. 

From what i see, it says to check the sensor with a multimeter to verify it's working, then check connections, and/or replace.

https://corolla-club.ru/doc2/rm04f1ru/repair2/html/frame_rm000000wby02fx.html

Thank you for that information, I will give that a try. 

[Tpatel]

Hi again, so now I got the car checked out and found the voltage reading on sensor 2 (post cat) is okay but sensor 1 (pre cat) is constantly on 0v. See attached video. I am wondering is there a fuse or something else which is causing sensor 1 to show no voltage?

Thanks in advance

[flash22]

It's not uncommon for the ecu to throw the wrong code - Remember the code is a diagnostic tool, not the cause, B1s1 is know as an air fuel sensor, the oem is Denso

replace the sensor

Denso part number is - DOX-0510

 

[Tpatel]

Hi, I replaced the part yesterday with a Denso part as you mentioned and still shows 0v. Making me wonder what could be causing this?

[furtula]

Could the the ECU is not able to communicate with the part, bad connection, broken wire, etc.

Did you try to measure resistance with the multimeter on the part old and new? 

You can refer to this manual for instructions how to test the resistance, which pins, values, etc. 
https://corolla-club.ru/doc2/rm04f1ru/repair2/html/frame_rm000000wby02fx.html

[flash22]

It's a fault in the plug/harness, check the plug is clean and has no corrosion also check the terminals are not spread apart too far, the check if you have the 12V, the next step is to check the wiring continuity back to the ecu

 

if you have access to another scan tool make sure it not just the scan tool acting up

[Tpatel]

Thanks for the replies, I will get this checked and update with my findings. 

[Tpatel]

On 2/18/2021 at 11:52 AM, Tpatel said:

Hi again, so now I got the car checked out and found the voltage reading on sensor 2 (post cat) is okay but sensor 1 (pre cat) is constantly on 0v. See attached video. I am wondering is there a fuse or something else which is causing sensor 1 to show no voltage?

Thanks in advance

Hi, so today I drove the car about 50 miles expecting the engine light to appear but it never came on. Sensor 1 and sensor 2 have been replaced with original Denso parts and when I use OBDII the voltage is still 0 on sensor 1. Is this normal? My engine light hasn’t come on so do I assume it’s all working fine?