Well, the problem could just be a dirty sensor or a faulty sensor than can be replaced cheaper than the whole assembly.

Casa never fixes components, they prefer to replace entire assemblies.

I suggest to go to a non-casa car shop to have a better diagnosis of the problem.

A shop like SPEEDLAB (located at Quezon Ave, tel 3764648/3764651) can help you just as well as the casa or even better.

http://www.speedlab.com.ph/