2000 Honda Civic Problems

Finally got this car to the garage today. The Honda garage scanned it and said it needs a S102 sensor. They have quoted £325.23 fitted. My questions are; What does this sensor do? Would an independent garage be able to do this repair? ...

Recently bought this car, low milage full history, starts and runs well enough around town, but problem comes on uphill sections, it's just so weak!! I have a '96 Colt 1.3 which, in the same stretches of road, doesn't even notice the secti...