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· Registered
19 Posts
Discussion Starter · #1 ·
I'm getting a P0431 code. The car has 112k miles and all four sensors are original. I'm sure they are long overdue for a change.
I use an app on my phone and I can show the 4 sensors on individual graphs.
The graphs show the pre-cat B1S1 & B2S1 voltage moving from a .i to .9v. If I understand, this pattern is OK.
The post cat O2 sensors are quite different.
The Bank 1 Sensor 2 shows a steady voltage of about .6v at idle.
The Bank 2 sensor 2 shows a steady but very low voltage of .1v at idle.
Both sensor respond to acceleration and seem to be going up & down voltage wise somewhat similar to the pre cat sensors.

It seems as though the B2S2 O2 sensor is dead.

I'm not too familiar with O2. Just reading up as best I can.

The car feels fine. It starts and runs OK. My mpg isn't great (16mpg average city/hgwy) but most of my driving is 65% around town and the rest highway.
I can't find or hear any vacuum leaks.

Could the low voltage be saying the O2 sensor is dead?


· PassatWorld Elder
28,082 Posts
As it does not affect MPG or anything really, you can wait to replace the B2S2 when it's time for inspection. I don't know if a spacer would solve the issue. Cut the wiring at both end of the trans (if it's a Tip), as it's difficult to remove. Then just connect the new wiring to the old where you can reach.
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