Skoda Octavia Checklist

One of the most common problems on the VAG 1.9tdi engine (both 90bhp and 110bhp) is the loss or hesitancy of power between 2000 and 3500rpm.
The cause for this can be one of a number of issues; however there is a few that are the most common causes.

1. Engine Control Unit (ECU) - Basically the VAG group acknowledges that there is a fault with the ECU on this engine and would normally advise you upgrade to the latest version. Be aware that this is a very expensive upgrade at somewhere around £600.
2. Turbo control valve - The 110 engine has a control valve on the turbo. This is a known fault and can be rectified by stripping it down and lubricating. This is normally a job for your main dealer and is a fault that should show up on sophisticated dealer diagnostics software. Be aware that if the problem recurs after this rectification, then you will probably need a new turbo.
3. MAF sensor - This is the airflow meter, it is located in the plastic air box pipe that leads from the air box to the engine and is secured by two screws. Sometimes these devices become clogged and or electrically malfunction. It is best to buy a new one rather than source a second hand item.
4. Turbo pipe - There is a small vacuum pipe that leads from the turbo to the ECU (it is about a foot long and looks similar to that of a bicycle pump valve). This pipe is known for splitting or leaking at the ends. Check that the pipe has no splits and that the ends are air tight by using small jubilee clips.
5. Vacuum pipes - Located on the bulkhead in front of the passenger seat is a connector block that has numerous pipes going to it. Check that all these pipes are in good order and connected properly. Replace them accordingly where necessary.
6. Fuel filter - These can become easily clogged by contaminants in the diesel. Replace the fuel filter with a new one that has been soaked in diesel treatment such as Redex etc. The engine may take quite a bit of starting after this process, but once started it will help to clear the fuel system. It is also a good idea to add some of the treatment to your fuel tank at the same time.
Although the loss of power can be caused by many things and finding a solution is often a process of elimination, the above are considered the most common causes and solutions.