bora diagnostic fault

**8215michaelb** · 27-12-2007,10:32 PM

hi
i have a 2001 115bhp(85kw) bora,i have a problem with the turbo which goes on to safe mode after a while. i took it to an independant who put it through a diagnostic check which found fault code 17965 charge pressure control positive deviation p1557-35-10 intermittant.(i dont think he had a clue how to fix it). i wondered if anyone knew what possibly was wrong and more importantly someone in the glasgow area who could fix it.
thanks michael

**Crasher** · 28-12-2007,12:26 AM

This is a very common problem on TDI's with what is known as a Variable Nozzle Turbine or VNT and sometimes referred to as a Variable Geometry Turbo or VGT, Goggle any of these and you will get a more in depth explanation. These nozzles or vanes get clogged up with carbon deposits and then the actuator which moves them can't move and this results in an over boost error that makes the ECU got into a safe running mode. Most people automatically remove the turbo and clean the vanes or even replace the turbo. I have found that using the commonly available piece of diagnostic equipment called VAG-COM, it is possible to put the engines computer into a special mode (Basic adjustment mode 04, display group 011) that lifts the engine revs to around 1400rpm and operates the actuator but this only works on PD TDI engines and the 115PS engine is a PD TDI. This period when actuation should be taking place is shown on the display screen as "ON" and at that point, a gentle tap with a long bar and small hammer on the actuator rod will usually free off the vanes. Left to run in this mode for a few minuets, the vanes gradually clear of carbon build up and then work correctly and this often saves the turbo being removed/replaced and therefore lots of time and money. If it doesn’t work, no damage will have been done and only about 15 minuets wasted.