# Code P015B



## jblackburn (Apr 14, 2012)

This is somewhat common with early Gen 2's.

There is an ECM update for 2016-17's to address this specific code. If it comes back after the reprogramming, replace the O2 sensor too.


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## _LadyCruze_ (10 mo ago)

Good to know. Thank you! @jblackburn


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## marmalou (Dec 30, 2020)

I had this code with similar minor hesitations when accelerating/decelerating. 

On the "eco meter" in the dash display, the meter normally goes down to zero when I let off the gas, but with this code I was seeing the eco meter go up, lag, and then eventually fall to zero when letting off the accelerator. 

I believe the ECM update is part of this TSB: https://static.nhtsa.gov/odi/tsbs/2017/MC-10139128-9999.pdf Although I have a 2017, it was not part of this VIN break so I did not go to the dealer for the ECM update.

The code did go away after a couple weeks, but then returned so I replaced the upstream O2 sensor. When it came out, it looked like this:









Put in the new O2 sensor and haven't had issues for the following 30,000 kms.


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## Bvogt (Dec 19, 2021)

Does make the mind go straight to the O2. You could swap the upstream with the downstream and see if the code changes location. Like swapping a plug


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## _LadyCruze_ (10 mo ago)

marmalou said:


> I had this code with similar minor hesitations when accelerating/decelerating.
> 
> On the "eco meter" in the dash display, the meter normally goes down to zero when I let off the gas, but with this code I was seeing the eco meter go up, lag, and then eventually fall to zero when letting off the accelerator.
> 
> ...


Thank you so much for the info! Gonna look into the problem this week on my day off. I'll give an update with what I find. 😄


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## Barry Allen (Apr 18, 2018)

jblackburn said:


> There is an ECM update for 2016-17's to address this specific code.


As a bonus, do you get the ECM update that helps prevent piston cracking?


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## jblackburn (Apr 14, 2012)

Barry Allen said:


> As a bonus, do you get the ECM update that helps prevent piston cracking?


Yes, that's part of the calibration too


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## _LadyCruze_ (10 mo ago)

Well I changed the upstream O2 Sensor. I'm experiencing little to no change in how the car drives but I did notice a slight change in Fuel Economy. I still need to look into the ECM update. Called a couple places for advice and I was told without an active check engine light there's nothing they can do for me even if I brought the car in. Troubleshooting for now it seems. Hopefully I find a solution.


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