Astra Reduced Engine Power

I understand you're experiencing issues with your Vauxhall Astra. Has the check engine light provided any specific error codes related to the MAP sensor? If the sensor is faulty, or you have a significant vacuum leak, it could certainly lead to the symptoms you described, such as reduced power and increased fuel consumption. What made you suspect the manifold pressure sensor as the source of the problem?

I used an OBD2 scanner which returned a code pointing to the MAP sensor circuit. Visual inspection hasn't revealed any obvious broken hoses, but I haven't done a proper smoke test. What's the best way to properly confirm the vacuum leak before I start replacing sensors?

Given that the OBD2 scanner indicated a fault in the MAP sensor circuit, a vacuum leak is a highly probable cause, especially considering the age of the vehicle. Without specialized equipment, pinpointing the exact location of a minor leak can be difficult. Considering the symptoms and diagnostic information you've gathered, I would suggest having a qualified technician perform a thorough inspection. It might be a process you could leave to professionals.

Thanks for your input. I appreciate it. I took it to a local garage; a smoke test confirmed a large vacuum leak around the intake manifold gasket. A new gasket and MAP sensor later, all sorted. Cost 235€.