P(ersistant)0156

"interstate366, now In The Industry" (interstate366) 03/15/2020 at 12:06 • Filed to: Aristo, Toyota Aristo, Lexus GS

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When I bought the GS back in December, the CEL was on for code P0156, the rear O2 sensor. It’s not THAT difficult of a fix, but it requires peeling back part of the passenger’s side footwell carpet because the plug is under the center console. Changed it out yesterday, took it out for a test drive, CEL came back on. Same code. What else would cause that? Exhaust leak, maybe?

jimz > interstate366, now In The Industry 03/15/2020 at 12:28

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that code means “ O2 Sensor Circuit Malfunction Bank 2 Sensor 2.”  which means the problem could be anywhere in the wiring between the PCM and the sensor. 

Dr. Zoidberg - RIP Oppo > interstate366, now In The Industry 03/15/2020 at 12:33

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One forum I read says the connector itself -- you know the ckicky thingie that connects to the new O2 sensor thingie -- was damaged/old enough that it won't recognize a new sensor. There should (hopefully) be a part number visible on the thing.

ClassicDatsunDebate > interstate366, now In The Industry 03/15/2020 at 12:37

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As the others said, check the connector.  I’d troubleshoot in this order: wiring, exhaust leak, faulty new sensor.

someassemblyrequired > interstate366, now In The Industry 03/15/2020 at 13:00

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Two things - if you didn’t erase codes, will take several startup cycles to clear.   The other thing that might help is cleaning the connector with contact cleaner and using some dielectric grease. 

interstate366, now In The Industry > someassemblyrequired 03/15/2020 at 13:03

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I unplugged the battery, and it came on after about 45 minutes of driving. I’ll try the connector.

sony1492 > interstate366, now In The Industry 03/15/2020 at 13:05

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If you have an obd reader to look at live data see if the sensor fluctuates between 0 .1v and 1v, if it does I'd start looking at exhaust problems.  The fluctuations would indicate the wiring is intact.

interstate366, now In The Industry > sony1492 03/15/2020 at 13:09

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Mine only reads and erases codes, but I’ll ask around.

interstate366, now In The Industry > ClassicDatsunDebate 03/16/2020 at 18:22

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It’s an exhaust leak. Confirmed today.

interstate366, now In The Industry > Dr. Zoidberg - RIP Oppo 03/16/2020 at 18:23

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Confirmed it’s an exhaust leak today.

ClassicDatsunDebate > interstate366, now In The Industry 03/16/2020 at 18:49

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well, at least its the most straightforward fix, hopefully.

Dr. Zoidberg - RIP Oppo > interstate366, now In The Industry 03/16/2020 at 19:44

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Could be worse!