Downstream O2 code.....then immediate US code after change?

[Rhill]

Hi guys,

The Sube has been throwing an 0137 code, bank 1 sensor 2 code.

I changed the downstream sensor and it immediately showed a code for the upstream sensor.

Odd. The car only has 70k miles, wondering if I toasted them both doing a seafoam cleaning.

Im hoping its not the CAT, but no other codes.

Maybe they like to be changed in pairs.

I used an NTK, so doubtful its an issue with the sensor.

Thanks in advance

Ryan

 

[thastinger]

I'm no expert but I believe they work off of differential, your short term fuel trims are controlled by the forward O2 sensors and the rear O2 somehow "makes sure" the cat is working.
Did you disconnect the battery when you changed out the rear sensor? If so, maybe you need a few drive cycles.

 

[Rhill]

Thanks thastinger,

I didnt dissconnect it, but I did reset the codes twice with an almost instant reappearance.

It might be worth disconnecting the battery and seeing if the car sorts it out.

Wishing I didnt soak the cat with WD40 fighting with the sensor

 

[dumkid]

Wd40 shouldn't hurt anything. If both 02 sensors are tired, then the computer will throw a code for whichever ones worse.

 

[Rhill]

Yeah, it just stunk!

as a follow up - if any of you have an issue with reocurring heater circuit codes....check your 20amp O2 sensor/heater fuse.

Mine must have tripped after the first install. I'm fine with having done both sensors, but could have been happy waiting.

Problem fixed with a $1 fuse

 

[MSCH]

basically they read upstream data as a starting point for fuel trim
and they read downstream data for cat efficiency or to double check the upstream.

now you try upstream...

 

[someonesomewhere]

basically they read upstream data as a starting point for fuel trim
and they read downstream data for cat efficiency or to double check the upstream.

now you try upstream...

Already fixed. It was a blown fuse.