Hello all. 

I have a little Audi A3 8p 2009.  125k or so. 19tdie

This morning I had a orange light start flashing and I have scanned and it says p0234 over boost. 

Any thoughts on what to check, clean in the first instance?   I stopped the car and then it disappeared.   No other issues at the moment.

Any common faults ?

Thanks for your help .

Edited June 27, 20241 yr by A3car19tdi

Just following on from this... Later this evening my brake padal has just really  got really stiff to press.

Are these two this possibly linked ??

Overboost Condition This is a signal that the turbocharger's boost system is generating pressure above the level expected by the engine or control module. The causes of this problem can be various:

Problems with the boost control valve (N75) - The N75 valve controls the operation of the turbocharger by regulating the boost pressure. If the valve is damaged or malfunctioning, this can lead to excessive pressure production, resulting in error P0234.

Damaged or worn turbocharger - Turbochargers can become worn or mechanically damaged, which can cause overcharging or other boost pressure problems.

Defective MAP (Manifold Absolute Pressure) sensor - The MAP sensor measures the pressure in the intake manifold. If it is damaged or incorrectly calibrated, this can lead to incorrect pressure readings and the P0234 error.

Problems with the exhaust or intake system - Leaks in the intake or exhaust system, as well as damage to the turbocharger cooling system, can affect the performance and proper operation of the turbocharger.

Problem with the fuel supply system - If the fuel supply system is not supplying the correct amount of fuel to the engine, the turbocharger may be operating at an excessive load, which can lead to excessive pressure production.

Of course, I have only outlined the most important and basic ones, but this is where I would start. 

Also could the battery be failing causing electrical issues? 

Following on from this, the next day I went to drive and the brake pedal was solid.  

Further inspection revealed the vacuum hose had split and come completely off from the vacuum causing loss of brake.  Would this had started to cause or have anything to do with  the Turbo over boost issue somehow ? 

20 minutes ago, A3car19tdi said:

Following on from this, the next day I went to drive and the brake pedal was solid.  

Further inspection revealed the vacuum hose had split and come completely off from the vacuum causing loss of brake.  Would this had started to cause or have anything to do with  the Turbo over boost issue somehow ? 

Hi no the vacuum circuit for the servo is completely separate and driven from its own pump, just change the MAP sensor that would be the cheapest option to start with it will also need adapting to learn its values.

Steve.