A2179 MacBook Air 820-01958-A (2020) with SMC error

[sekidata]

This 2020 Air came in with a liquid-damaged trackpad & cable, which I replaced. It starts up and works normally but AHT brings up the error PFM006 ("There may be an issue with the SMC").

I know the SMC is integrated into the T2 on these models, so I performed a DFU Restore, which did not change the situation. I also tried a different battery (no change). I tried unplugging the trackpad/keyboard before running AHT (no change).

 

[2informaticos]

The problem is not the SMC, but some thermal sensor.
PFM006 is usually related with trackpad sensors.

Be sure to get correct levels for 3V3/5V_G3S voltages at J6700.
Inspect j6700 for corrosion and check the solders.
Also check Q6861 and related resistors (page 54).
Be sure to get good trackpad flex; do not trust too much new chinese flex.

 

[sekidata]

You were absolutely right. When I replaced the trackpad again, the SMC error disappeared. Turns out the initial replacement trackpad was bad.