Trouble code 00561 - Mixture Adaptation: Adaptation Limit (Add) Exceeded

[FrenchAudi]

I have this recurrent fault code in Engine Electronics. If I clear it, it returns next time I drive the car.

Ross-Tech suggests the following symptoms:

• Engine Jolting
• Increased Fuel Consumption
• Poor Idling/Jolting
• Reduced Boost Pressure

The engine is not jolting nor idling poorly, the fuel consumption has not changed noticeably (9.1 litres/100 km, = 31 mpg over the last 1200 km), and there does not seem to be any loss of power.

The engine does seem more reluctant to start, it sometimes turns over maybe 3 or 4 times before it fires, but at other time starts almost immediately. Whether the engine is hot or cold doesn't seem to affect this.

I have no ready means of measuring the boost pressure, but don't know what it was before, so there is nothing to compare it with.

Ross-Tech possible causes are:

• Mass Air Flow Sensor (G70) faulty
• Fuel Pressure too Low
• Leaks in Intake Air System and/or Exhaust System
• Injector(s) faulty (i.e. coked)

The easiest item to check there is the MAF sensor, is this accessible from inside the air cleaner cover? and if so, how can I test it?

With such a low mileage I am a bit doubtful that the fuel pump is worn out or the injectors coked on a petrol engine with injectors in the manifold, and I can't find any air leaks.

I suppose what I really need to know is whether this is a serious fault, and should I spend time investigating it?

[FrenchAudi]

For all those who have been avidly following this thread, I found the problem.

I had removed the PCV valve, to see if it was the source of the oil in the inlet tract, and sealed off its associated piping.

Unfortunately one of the 10 mm rubber ferrules I used to close off the connection to the inlet manifold had a small, about 4 mm, hole drilled in it, and, by sod's law, that is the one I used.

This must have played havoc with the mixture control.

I have now replaced the PCV valve and its piping, and cleared the fault, which has not reappered.

EDIT: Removing the PCV valve made no difference to the amount of oil appearing in the inlet tract, which must be coming from the turbo.