The differences you are seeing may simply be well within the acceptable allowed deviation by the manufacturer? Without knowing what Bosch's +/- allowable standard deviation standards are, it will be hard to compare sensors based on reading inputs alone.
Only true way to compare different sensors would be to bench test their readings and compare values against certified calibrated instrument standards for both barometric pressure and temperature over their full range of operation.
I do find it odd that you found that much difference between the two units you read, but without having a greater amount of sensors available to establish some sort of baseline readings of which to be able to compare against, one of your units may simply be a faulty sensor and its readings are outside of its respective allowable deviation standards specifications...
I am no expert on this; I do have information on file for the two sensors and someone who has an instrument test background may understand some of these numbers and their comparative pressure/voltage relationship curves over their respective operating ranges? There are slight differences in their curves I am sure...
0 281 002 845 3 bar (11 kPa @ 0.25V , 307 kPa @ 4.75V)
Bosch 3.0 Bar T-Map Sensor / 0 281 002 845
Scalar A - 279.5555528
Scalar B - 0.23529412
Offset - 5.44444 (repeating)
using 65.7777 as the first multiplier, 1 as the second multiplier, and 5.4444 as the offset/additive.
= 11.0 kPa at 0.25v, 300.4219 kPa at 4.65v, and 306.9997 kPa at 4.75v0 281 002 437 3 bar (20 kPa @ 0.4V , 300 kPa @ 4.65V)
Bosch 3.0 Bar T-Map Sensor / 0 281 002 437
Scalar A - 65.88
Scalar B - 1
Offset - 6.353
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