SQ5 TDI Boost Sensor Failure Causing Performance Loss

A similar issue occurred with my 2016 A6 3.0 TDI. The boost sensor and air intake system showed comparable symptoms, engine light activation, power loss, and irregular turbocharger behavior. The whistling noise and jerking during acceleration often points to boost pressure sensor problems rather than a complete turbocharger failure. In my case, the engine light was triggered by a faulty connection between the pressure sensor and its wiring harness. The connector had corroded over time, causing inconsistent readings. The repair involved cleaning the connection points and replacing the boost sensor assembly. This was significantly less expensive than turbocharger work. While the symptoms seem severe, they typically stem from the sensor not properly communicating with the engine management system. The increased fuel consumption occurs because the engine runs in a safe mode when it cannot accurately read boost pressure. The complete diagnostic process should include checking the air intake system for leaks and testing the sensor circuit before replacing parts. This is generally a moderate repair that requires proper diagnostic equipment to confirm. While concerning, these symptoms rarely indicate serious turbocharger damage when caught early.

Thanks for sharing your experience. I had nearly identical problems with my SQ5 last year, the check engine light, boost issues and that unnerving whistle noise during acceleration. My intake manifold also showed signs of wear when they inspected it. Did you get the final repair cost? Curious how it compares to what I paid. Also wondering if youve had any recurring issues with the turbo boost system since the fix? Sometimes these sensor problems can indicate other developing issues with the air intake system that show up later. The diagnostic process you described matches what I went through, really important to verify the sensor connections before jumping to major repairs.

Thanks for asking about the follow-up details. After seeing my mechanic, it turned out the bad boost pressure sensor was exactly the issue, just like we suspected. The repair came to 95 Euro, which covered fixing a defective cable connection to the sensor. This was much more reasonable than I initially feared. The turbo system has been running perfectly since the fix, no more whistling noises or power issues during acceleration. The intake manifold and air intake components all checked out fine during inspection. Fuel consumption returned to normal levels once the pressure sensor was communicating properly with the engine management system. I monitor for boost leaks more carefully now, but havent experienced any recurring problems in the months since the repair. The original symptoms completely disappeared after addressing the faulty sensor connection. Getting the proper diagnosis definitely saved money compared to unnecessary turbo repairs.

Thanks for the input. I finally got this sorted out last week. Took it to a new mechanic who actually spent time diagnosing before replacing parts. Turned out my boost sensor was failing intermittently due to a damaged wiring harness near the intake manifold. The engine light would trigger when the connection got weak during acceleration. Total repair came to 280 Euro including diagnostic time and parts. The mechanic also found and fixed a small air intake leak while checking the system. Since the repair, the turbocharger is working perfectly, no more whistling or jerking. Fuel economy is back to normal and the engine runs smooth even at idle. Really glad I asked here first and focused on the sensor/electrical issue rather than assuming the worst about the turbo. The symptoms were scary but the fix was straightforward once properly diagnosed. No issues since the repair and the engine light has stayed off.