Sudden P0141 - for all three 02 sensors at once - make sense?

[DOGFACE]

Sooo... I have put around 1000 miles on a recently purchased '97 Yukon 2 door with Vortec 5.7. 177K miles, with a replaced engine.

A few weeks ago, the check engine light on. A few days ago. the light turned off. Today, it came back on. I checked for codes, which returned faults in all thee 02 sensors.

Does this make sense that all three would go **** up at once, or more likely that all three were bad a long time ago? Or... is there something else to consider?

I plan a complete new dual exhaust in a couple months, and then tune. Should I screw with the sensors now, or just wait will the exhaust is upgrade and knock out in one shot?

 

[east302]

Is it just the one code P0141 (bank 1, sensor 2) or are there more?

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[DOGFACE]

Three separate codes,

Bank 1, Sensors 1 and 2

Bank 2, Sensor 2.

Hmm, thought I only three sensors... apparently, I have four.

 

[evilunclegrimace]

If the Yukon is set up like the Suburban the fourth sensor is on the intermediate pipe behind the mating flange

 

[Jglew82]

Recently replaced engine... Check all the engine grounds. The O2's share a common ground at the Right front engine block, and may not have been secured correctly upon replacement. Check those. Also check for battery voltage on the pink wires to all sensors. If you don't have power, check the ENG-1 Fuse. Start there and see what you come up with.

Edit: also check your PCM connectors for tightness, I find it interesting that the only code not mentioned is Bank2 sensor1, which is the only sensor that has its "lo" signal on a non-consecutive numbered connector pin.