I’ve got a ‘97 B5 A4 1.8T AEB.

Been stuck in limp mode (max boost 4psi on external gauge) for quite a while. It does boost to 12-14 (mtm stage 1 ecu) sometimes but I noticed this was only when the airbag light was off.

The motor has been swapped (head gasket) but the issue still persisted. Have tried scanning the car with VCDS but am unable to pull any engine codes for some reason.

Any ideas what could be causing the airbag light to be on? Nothing showed up in the last scan but can do another one.

Also would like to fix the engine code reading issue. No obvious wiring issues so unsure what it could be.