High voltage and oxygen sensor code

I am getting a high voltage bank 1 sensor 2 oxygen sensor code. Replaced oxygen sensor but check engine light still on. 2015 4x4 base with manual trans and 2.7 engine. 38,000 miles. Damp conditions also seem to affect the light as well.

 

Did you clear the code after replacing the sensor?

 

Yes

 

Did you replace the right sensor?

 

Yes

 

Have you checked for an exhaust leak?

 

What was the brand and part number replaced?

Code P0138 Common Diagnosis Mistakes
Replacing the O2 sensor without checking any wires or clogged/damaged catalyst.

 

Bosh sensor. Took it to Toyota and everything working correctly. Other than suggesting genuine Toyota part they were much help

 

Bosch makes notoriously garbage sensors. That could be the culprit. Otherwise if you're only getting the code intermittently (you said wet weather is effecting it - how exactly?) then I would also inspect the wiring and connections.

 

When it rains or snows. Light comes on and goes off when things dry out. Mechanic checked wiring. Said he didn’t see anything wrong. Had read that upstream sensor gives and false reading to the downstream. Has anyone heard or experienced that?

 

IMO, if it acts up with moisture it is a sign of a wiring issue. I would check it closer. You might also want to put some dielectric grease (silicone grease) in the O2 connector at the harness to seal it. The 02 sensor works on a very narrow voltage window. Any wiring issues that create voltage reference issues will show up quickly.

 

That is what my mechanic did. Light went off this morning. I’ll see next rain what happens. Just trying to get a jump on things just in case

 

If you check wiring/connections and can't find anything I'd bet that bosch sensor is the problem. I've had a bad experience with a brand new O2 sensor of theirs throwing a code in the past.

 

Another thing to check, (I know it's obvious but just trying to troubleshoot), make sure the sensor is tight against its compression ring. I have had 02 sensors that were not completely tight cause issues.

 

Just weird that with the light on according to Toyota everything is working fine

 

Well, I would hope they did not tell you that with the light on!

 

You can always swap sensors btw Bank 1 and 2. If the problem follows, you have a bad sensor. If not, start looking at the wiring.

 

Bosch is trash for oxygen sensors. If and when the light comes back on, replace the sensor with a factory or OE equal (Denso).

The upstream CAN cause false readings for your downstream but you only have 38K and the chances of that sensor being bad is really slim.

Regardless, you are covered under 8 yrs. 80K federal emissions warranty and oxygen sensors fall under that warranty blanket, so you should not even have to be worrying about this sort of stuff right now. Go have dealer set your truck straight.

 

They did. Light was on. They suggested waiting till the sensor failed since it was working properly or going to a Toyota sensor.

 

I was told oxygen sensor was not covered under emission warranty. Two different dealers told me that.