Your Subaru does not have a sensor in the spare unless you installed it. Subaru has never put a sensor in the temporary spare tire and they have never had a vehicle that can hold more than 4 codes. At least not in the United States. I will wager any amount of money on this. If your light went out after you inflated the spare, it was coincidence.

As for the Fit, also pure coincidence. As of 2015+, there are no sensors in the wheels. It just monitors wheel rotations via the same sensors it uses for traction control. The system cannot monitor the spare while it is in the trunk.

 

Is there any advantage or disadvantage setting the tires to 35psi rather than 33/32 per the specifications?

 

(((( Bump ))))

 

OP here. Well, I brought the car into the dealer, and just heard back that they noticed one tire had a different tread than the others, and asked if I had a tire replaced recently. Well yes, I did have a tire replaced, but it was a couple of years back. The dealer believed that the light is being triggered by the difference in tread depth between the one new tire vs the three old tires, and suggested I get new tires. I told them I'd think about it, since I believe the old (original) tires still have some good life in them (there is 21K miles on the car).

Thanks for everyone's input.