CHR Hybrid Boost Pressure Issue

The symptoms you describe certainly point towards a potential issue within the boost pressure regulation system, especially given the presence of both whistling and hissing noises. A failing wastegate valve is a plausible cause, but we can't rule out other possibilities without further investigation. Has the vehicle undergone any recent maintenance or repairs that might be relevant? Additionally, have you attempted any diagnostics yourself, such as reading the error codes using an OBD-II scanner? Understanding the specific diagnostic trouble codes (DTCs) stored in the engine control unit (ECU) would be extremely valuable in narrowing down the potential causes. Furthermore, checking the integrity of the MAP (Manifold Absolute Pressure) sensor and associated vacuum lines is advisable.

Thanks for the detailed response. I haven't had any recent maintenance that would be relevant. I did get the following error codes: P0299 and P0046. Does that help narrow it down? I've checked the MAP sensor visually, but I don't know how to properly test it.

The presence of error codes P0299 (Turbocharger/Supercharger Underboost) and P0046 (Turbocharger/Supercharger Boost Control 'A' Circuit Range/Performance) strongly corroborates the suspicion of a wastegate valve malfunction. While a visual inspection of the MAP sensor is a good start, it doesn't confirm its functionality. The MAP sensor provides crucial data to the ECU regarding intake manifold pressure. If the sensor is faulty, it can lead to inaccurate readings and consequently affect the wastegate valve control. However, given the error codes and symptoms, the defect most likely lies in the wastegate itself, or the vacuum lines that control it. I highly recommend taking your vehicle to a qualified workshop equipped with diagnostic tools and expertise to properly diagnose and rectify the issue. Continuing to drive with a faulty boost pressure system could lead to further engine damage.

Thank you for the detailed and helpful information. I appreciate you explaining the function of the components and suggesting the next steps. I took it to a workshop, and you were right: the wastegate valve was indeed faulty. The repair cost 860€.