2009 Dodge Journey P0234 Turbocharger Issue: Symptoms, Diagnosis, and Dealer Visit Advice

Hi everyone, I recently purchased a used 2009 Dodge Journey and have been experiencing recurring issues within the first week of ownership. After driving approximately 40 miles, when I reduce speed to 50 mph, the engine revs unexpectedly spike, followed by noticeable shifting problems. This vehicle has an automatic transmission and runs on diesel fuel. The issue only occurs during operation—once I pull over and turn off the key, the symptoms disappear for another 40 miles before recurring. I used a diagnostic kit to check the system and found fault code P0234, which indicates a turbocharger pressure sensor or related component issue. I'm now unsure whether I should address this immediately with a repair, or take it back to the dealer where I bought it (about 4 hours away). The dealer seems to be suggesting that I return for service, but I'm concerned about potential engine damage from continued driving. I've already spent £530 on an alternator replacement from Arnold Clark, who claimed it was faulty—however, after further investigation, I suspect they may have misdiagnosed the issue. As a woman buyer, I feel there's a possibility of being misled or overcharged. Any insights into whether P0230 is actually related to turbocharger problems, and what steps I should take next would be greatly appreciated.