Mac sensors reference designators

SMC sensor codes (reported in ASD) can be quite cryptic and there is no way to immediately know which component it refers to on the logic board.
Some schematics have the sensor code next to the component, some don't. Some schematics tell the description for a group of sensor, some give a hint on the placement, but sometimes it is wrong.
Remember that when you have an issue on an SMBUS, you will have multiple sensors showing an error, all related to the same sensor hub on that specific SMBUS, but it may be caused by something else (eg. ALS or Touchpad).
Warning: this is a work in progress. The information here has not been exhaustively verified! This is mostly guess work from the information in the schematics, the boardviews, the ASD sensor lists and reports of correlation between sensors found on the web.
Warning 2: when using a monitoring software such as HWMonitor, the sensor descriptions may be wrong. It may even hide some sensors and show missing ones.
==List of abbreviations used in sensor descriptions==
*TBT = Thunderbolt
*T29 = Thunderbolt controller
*MLB = Main Logic Board
*BOT = Bottom
*TBD = To Be Determined (ie. no information in this schematics revision)
*BMON = Battery Monitoring
*AMON = AC Adapter Monitoring
==Replacing temperature sensors==
===Carefully check the datasheet of the sensor you are trying to replace.===
===Example:===
TMP461 (known as U5850 on 820-00239 - Thunderbolt die, Airflow Left, but widely used on Macbook board) as several ground pads. It's close to the edge of the board and is sometimes teared off by careless repair shops... Pads 5 and 10 are actually used to determine the I2C address. They can be GND, floating, or VCC. These pads can be ground or pulled high, and must grounded or pulled high carefully (like...when the lines have been raped... We've all been ther) so that the sensor is recognized. 
It may be similar for other sensors references.
==MacBook Air==
===MacBook Air 11" 2013 820-3435===
Matching between reference designators and sensor description is different from the MacBook Air 13" 2013 820-3437.
MacBookAir6,1 in SMC Sensor Codes.
Schematics contains gives wrong hints about sensors.
Temperature sensors
SMC Sensor Code	Description 	Reference designator	Bus
TS2P 	Memory Proximity 	Q5810 	SMC S0 "1" SMBus
THSP 	T29 Proximity 	Q5820 	SMC "3" SMBus S0
Ta0P 	Inlet 	Q5830 	SMC S0 "1" SMBus
TW0P 	Wireless Proximity 	Q5840 	SMC "3" SMBus S0
TM0P 	Camera Proximity 	Q5850 	SMC "3" SMBus S0
TCHP 	Charger Proximity 	Q5860 	SMC S0 "1" SMBus
TC0P 	CPU Proximity 	U5800 	SMC S0 "1" SMBus
Tm0P 	Logic Board Top Side 	U5810 	SMC "3" SMBus S0
Ts0P 	Trackpad 	J4800 	SMC "3" SMBus S0
TB0T 	Battery 	J6950 	SMC "5" SMBus G3H
TB1T 	BMU 1 	J6950 	SMC "5" SMBus G3H
TB2T 	BMU 2 	J6950 	SMC "5" SMBus G3H
Th1H 	Fin Stack 	J9500 	SMC "2" SMBus S3
TCXC 	CPU Core PECI 	U0500 	PECI
TPCD 	Platform Controller Hub	U0500 	PECI
===MacBook Air 13" 2013 820-3437===
MacBookAir6,2 in SMC Sensor Codes.
Schematics contains gives wrong hints about sensors.
Temperature sensors
SMC Sensor Code	Description 	Reference designator	Bus
TS2P 	Camera Proximity 	Q5810 	SMC S0 "1" SMBus
THSP 	T29 Proximity 	Q5820 	SMC "3" SMBus S0
Ta0P 	Inlet 	Q5830 	SMC S0 "1" SMBus
TW0P 	Wireless Proximity 	Q5840 	SMC "3" SMBus S0
TM0P 	Memory Proximity 	Q5850 	SMC "3" SMBus S0
TCHP 	Charger Proximity 	Q5860 	SMC S0 "1" SMBus
TC0P 	CPU Proximity 	U5800 	SMC S0 "1" SMBus
Tm0P 	Logic Board Top Side 	U5810 	SMC "3" SMBus S0
Ts0P 	Trackpad 	J4800 	SMC "3" SMBus S0
TB0T 	Battery 	J6950 	SMC "5" SMBus G3H
TB1T 	BMU 1 	J6950 	SMC "5" SMBus G3H
TB2T 	BMU 2 	J6950 	SMC "5" SMBus G3H
Th1H 	Fin Stack 	J9500 	SMC "2" SMBus S3
TCXC 	CPU Core PECI 	U0500 	PECI
TPCD 	Platform Controller Hub	U0500 	PECI
===MacBook Air 13" 2015 820-00165===
MacBookAir7,2 in SMC Sensor Codes.
Warning: HWMonitor may show a non-existent "Meomory Proximity" and hide "Thunderbolt Proximity"
Schematics contains gives wrong hints about sensors.
Temperature sensors
SMC Sensor Code	Description 	Reference designator	Bus
TS2P 	S2 Camera Proximity 	Q5810 	SMC S0 "1" SMBus
THSP 	T29 Proximity 	Q5820 	SMC "3" SMBus S0
Ta0P 	Air Flow 	Q5830 	SMC S0 "1" SMBus
TW0P 	Wireless Proximity 	Q5840 	SMC "3" SMBus S0
TM0P 	Memory Proximity 	Q5850 	SMC "3" SMBus S0
TCHP 	Charger Proximity 	Q5860 	SMC S0 "1" SMBus
TC0P 	CPU Proximity 	U5800 	SMC S0 "1" SMBus
Tm0P 	Logic Board Top Side 	U5810 	SMC "3" SMBus S0
Ts0P 	Trackpad 	J4800 	SMC "3" SMBus S0
TB0T 	Battery 	J6950 	SMC "5" SMBus G3H
TB1T 	Battery Sensor 1 	J6950 	SMC "5" SMBus G3H
TB2T 	Battery Sensor 2 	J6950 	SMC "5" SMBus G3H
Th1H 	Fin Stack 	J9500 	SMC "2" SMBus S3
TC1C 	CPU Core 1 	U0500 	PECI
TC2C 	CPU Core 2 	U0500 	PECI
TCGC 	Intel GPU 	U0500 	PECI
TCSA 	CPU System Agent Core 	U0500 	PECI
TPCD 	Platform Controller Hub	U0500 	PECI
===Repair section===
In most cases failed sensors is rather a communication line problem. Since it is shared between multiple sensors, it might cause lots of different issues. For example, failed ALS sensor on the display side might cause malfunctions of amost all thermal sensors on board, simply because it is pulling shared SMC SMBus line to ground. 
==820-3437-B multiple sensor issues==
The problem:-
70% CPU usage when idle, machine slow and you may need to hold the power button to get the system to boot, however, sometimes the system still fails to power.
ASD faulting sensors (IC0R, ID0R, IM3C, ISDC, PB1R, PC0R, PDTR, PPBR, PSDC, VC1C, VCS0, VP0R). Device takes 0.06MAh.
Issues found/fixed:-
PBUS_S0_VSENSE missing - Q5500 Pin 3 via severely corroded. Ran jumper to R5503 Pin 1 to restore, issues persist.
C5021 turned into 1Ω. Capacitor replaced, issues resolved, and ASD passed diagnostics.
Addition:- 
I had an issue with C5021 again (21st September 2021) and this time the machine would not power on and PM_SLP_S4_L was missing. A quick check of C5020, C5021 and C5125 showed they were shorted to ground through C5021. Replacing C5021 (1uf X5R 0201) fixed the issue and the machine boots again. If there is a short in this area, it can cause all sorts of issues.
Category:Mac 
Category:MacBook 
Category:MacBook Air
Category:MacBook Pro