My wife has had her A4 cabriolet for 13 years and overall it has been very reliable. It is a 3.0tdi quattro S-Line ASB engine 2006. From time to time the particle filter light has come on. Normally if we just drive it in third gear for about 25km 2500rpm it clears and does not come back for a couple of years. Last week it came on again, I drove as before for a while and the light went out, but yesterday it went into limp mode. The particle filter warning light has not come on, but the engine glow plug light started flashing on and off, it has never done that before, nor has it been in limp mode before. The glow plugs were changed a couple of years ago, by VW. The yellow engine warning has been on for a couple of days before the particle filter issue with Mass Air unit codes 000260 and 000258 showing, I have ordered a new mass air sensor and air filter and DPF code 009263 is still showing. I do not understand why the glow plug light is flashing instead of the the DPF light.