Intake manifold sensor

I don't know which sensor you're referring to or why it is suspect but I can offer a suggestion. If a mechanic diagnoses the cause of a problem, that diagnosis includes replacing the part to verify the problem is solved. Since half of the job was done by you, it suggests the mechanic did not actually do the diagnosis. Instead, he likely read the diagnostic fault codes and left the interpretation up to you or he added his best guess.

Diagnostic fault codes never say to replace parts or that one is bad. They only indicate the circuit or system that needs further diagnosis, or the unacceptable operating condition. When a part is referenced in a fault code, it is actually the cause of that code about half of the time. Your problem is related to the other half. Before replacing parts, the wiring must be inspected for grounded or cut wires, stretched or corroded connector terminals, and mechanical problems related to that circuit. A part is only replaced after all other potential causes are ruled out.

In this case you can likely use the new part to rule that out as the cause of whatever the concern is.