DSH

I have a 2005 S type diesel with the turned down exhaust pipe. It has done 142000 miles and had new turbos under warranty at about 25,000miles. I have a similar problem in that the "Reduced performance" message would appear for between 1 and 20 minutes after a warm start - but there was no reduction in performance and the mpg seemed OK. I took it to a main dealer who did a health check! They told me my near side EGR valve was failing. I bought one on line and got a local mechanic to change it. A few days later the message re-appeared. So I bought a cheap code reader that could also reset fault codes. It tells me the fault code is P132A with a hexadecimal number 07E8. If I reset the fault code and do a totally cold start it won't display the message, however many miles I drive. Stop the car for any time up to about 5 hours and the fault reappears immediately when it's restarted, but only for a few minutes then goes out leaving the orange engine shaped symbol on. The performance is fine and so is the mpg. Is this a turbo failing or some other component?