Originally Posted by GVK.

Surely if the light is on there must be a fault code? Have you give it chance to log a code by ignition cycle on/run/off a few times?

Assume this is on the Octavia VRS?

To see if it's mapped,one test, is to do a vag-com/vcds MAF airflow test on the live data measuring blocks.

You can roughly work out the bhp from the airflow. (providing the MAF is good)

http://wiki.ross-tech.com/wiki/index.php/Fuel_Trim_Info



150hp should see 120 g/s , so that's 120 divided by 0.8 = 150
180hp should see 144 g/s
225hp should see 180 g/s
250hp should see 200 g/s

You get the idea.

Another check is to test the boost pressure, pretty sure most 1.8ts stock run around 0.6-0.8bar.

Further than that you need someone who knows what they're doing with remap files to pull the software off the car and go through it to see if it's stock or 'tuned'.