The March 2015 update of Apple's 13" MacBook Pro Retina Display, model A1502, features fifth-generation Intel Core i5 and i7 processors and introduces the Force Touch trackpad.

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Battery Failure: Open Thermistor

Hello everyone. Yesterday my MBP rebooted randomly and showed my battery status to "Replace Now". It now shuts down when unplugged from the AC Adapter, and will not boot from battery power. These are the stats from System Profiler:

Model Information:

Serial Number: <<redacted>>

Manufacturer: SMP

Device Name: bq20z451

Pack Lot Code: 0

PCB Lot Code: 0

Firmware Version: 702

Hardware Revision: 1

Cell Revision: 3224

Charge Information:

Charge Remaining (mAh): 5633

Fully Charged: No

Charging: No

Full Charge Capacity (mAh): 5960

Health Information:

Cycle Count: 376

Condition: Replace Now

Battery Installed: Yes

Amperage (mA): 0

Voltage (mV): 12758

Clearly the battery is still fairly new, with a good amount of capacity and cycles left.

Running TechTool, the battery health check shows 1 failure: Open Thermistor. I have opened up the case to inspect the circuits and found no loose connections or corrosion anywhere (I have never had any spills on the laptop).

Also, running a sensor check in TechTool shows Battery TS1 and TS2 to be at 32C and 29C, respectively, and Passed.

I have tried doing an SMC reset to no avail. Anyone else know what I can try? Or am I better off just replacing the whole battery? Just seems wasteful to replace it given its cycle count and capacity.

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1 Answer

Chosen Solution

Replace the battery. There is likely a bit of liquid damage on the battery PCB, under the sticker

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Thanks for the advice. I've ordered a replacement battery. Have to admit I'm not looking forward to dealing with all this glue...

Just out of interest, since the error is saying the thermistor is open, i'm guessing the resistance is set at infinity (i.e. no current going through), would water damage do this? Wouldn't moisture create a short circuit and setting the resistance closer to 0? Do correct me if I'm wrong.

Also, since it's just one component giving me a false reading, can it not be cleaned? Or is it not worth trying?


To be honest, I don't run battery health check programs when the battery status is bad, I just replace it. Whenever the battery status is "service soon", "replace now", etc, it is always an issue related to the battery. You can try cleaning the liquid damage on the battery PCB, however I have never had any luck doing this.

Usually when resistors fail, the resistance goes up (1mil+ usually), probably is the same situation with thermistors.


@reecee Coconut Battery is one of the most useful diagnostic tools I use, it even helps me with iOS devices:


Thanks for the post.

I just got a brand new iFixit battery replacement installed and experiencing the same issues. CoconutBattery has identified that the battery error is Open Thermistor, no spillage, fresh out of the box :(

hopefully i get a working replacement replacement :)


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ruslanm will be eternally grateful.
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