Third O2 sensor this year.

Hey guys. My truck is spitting a p00138 code again. It's telling me that the bank 1 sensor 2 sensor is bad and this is the third time I've had to replace that sensor in one year. Anyone know why this one keeps going bad?

 

Do you test the sensor when you take it out? How do you know its bad?

 

No I haven't tested them. The last one was still under warranty. It only took two months for the code to throw again.

 

I don't have a great place to work on my truck these days so I just changed it last time without testing it. How do you test it?

 

I suspect the sensors are not bad. Something else is going on

 

Any ideas?

 

Based on the symptoms, a corroded connection in the harness somewhere seems likely.

 

What's the fix? Do I need to replace the harness or even the harness mount?

 

If B1S2 keeps triggering its usually the upstream a/f sensor giving wrong readings.

It's complicated but its common on Toyotas. Harnesses or wiring is not common, but a possibility.

If you have the freeze frame of the error share the voltage of b1s1 and b1s2.

It's 100% not b1s2 thats established.

 

Ok. I'll try and get the voltage. If not the harness then what's the next possibility?

 

B1S1

Edit, to be clear, what side of the truck is the sensor you changed?

 

I replaced that one, 1 year ago as well. It was a bitch to remove and we had to retap the threads

 

Both passenger side. Upstream and downstream

 

Very Good

 

I don’t have the right reader to get the voltage

I don’t have the right reader to be able to see the voltages. I took these pictures of the harness.

 

Do you know what type of reader I need to get to be able to record the voltage at the sensors?

 

OP, are the sensors OEM denso brand? Using any other ones from a local parts store is likely your issue.

 

They're denso

 

Look into OBD2 scanners that can display O2 sensors voltage.

 

Well the check engine light turned off. I’m going to clear the code and keep track of how many miles before it comes on again. I guess I’ve bought myself some time for now. It’s officially an intermittent problem.