Forté Technical Tips – Positive Crankcase Ventilation Valve Issues found in Audi A4’s


Audi A4 2.0 16V TFSI (CDNC), 2009-2012


Audi A4 fitted with 2.0 16V TFSI (CDNC) from 2009 to 2012 can show concerns at idle such as rough idle, noise and engine warning lamp on.


If DTC’s P0507 (Idle Control System RPM Higher than Expected) and P2187 (System Too Lean at Idle) are stored, then the PCV valve (Positive Crankcase Ventilation) is to be checked. If the PCV is clogged with oil residues, then this valve must be replaced. PCV is a valve that control engine oil vapour flow through the intake manifold, and this flow will vary depending on engine speed. When the PCV is clogged the excess of pressure in the crankcase won’t be eliminated and this will lead moisture and acids in the engine oil that will cause wear to the engine. The excess of pressure will lead to more blow-by past the pistons contaminating the piston rings and the combustion chamber.

In a direct injection engine, fuel is injected directly into the combustion chamber as opposed to injection before the intake valve. Due to their location, the injectors are exposed to more heat and pressure and costly materials and higher-precision electronic management systems are required. Direct injection offers alternative methods in fuel distribution with wall guided, spray-guided and air guide applications using different manifold and piston configurations and intricately shaped injector nozzles to direct the fuel and air mixture to the point of ignition improving combustion efficiency.

Contaminated Injectors can have a dramatic effect on the operation and fuel distribution. Poor injector spray patterns lead to incomplete combustion. This will increase contamination build up in other areas of the engine including Oil system, Intake system and EGR, turbo, catalyst and GPF. As incomplete combustion occurs pressure in the combustion chamber increases and in turn increases the pressure in the crank case requiring more reliability from the crank case breather system. Keeping the fuel and oil system clean will maintain efficiency and fuel delivery.


To fix this concern is advised to replace the PCV valve and clean the engine lubrication system with New Generation Engine Flush. This will remove acid, moisture, sludge, and soot from all the engine components and oil channels and will restore engine efficiency. It’s also recommended to carry out an injector clean with Petrol Specialist Injector Cleaner to clean and remove soot in the injector tips and on the piston top to restore air/fuel flow.

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