chrisj

[chrisj]

Hello everybody just joined so thanks for having me. Own an audi A4 2.0 TDI 2005 which was not accelerating as it used to.
A pal did a diagnostic check which showed fault 16618 boost pressure regulation limit exceeded. Is this easy to repair and how do you access the relevant parts.

Thanks Chris.

[cats81]

I have the same issue. If you find out let me know.

[Burgess_M]

Say you are plodding along gently in second or third then put your foot down, does the turbo kick in and then suddenly drop out? (as if you feel it boost for about a second or 2)
If so, Air Mass Meter or known as Mass Air Flow sensor. Thats where my money would be, common problem.

[BVR Automotive]

Although it is common for performance faults the air mass meter doesn't control boost pressure so wouldn't cause the boost limit to be exceeded, it could cause under boosting though.

Boost is controlled by a solenoid that controlls the amount of vacuum applied to a diaphragm which in turn moves a rod on the turbo that reduces/increases the amount of boost.
Boost is measured by the MAP sensor and this information is fed back to the ECU.
The ECU then controls the solenoid by duty cycling the voltage to it.

Excess boost can therefore be caused by faulty wiring to the solenoid, a fauly solenoid, split/blocked vacuum pipe, siezed rod on the turbo, a faulty MAP sensor or wiring to it.

Hope this helps but either way it will need further diagnosis.

Dave