HELP- Under Boost Warning & Limp Mode

[stevekoz]

Hi All,

I've got a 06 plate Audi A4 B7 TDI avant. Its the 170bhp model which has had a remap to approx 200hp.

I've recently had an issue with a re-occuring fault light/message and the car going into limp mode. I've had a VAG specialist look at it and on the first occurrance they checked turbo (newly replaced inlast 12 months) - not that, all clear. Couldn't find any faults and so cleared the light and it came back.

So had it back to them. The data logged it - same error message - underboosting. But nothing mechanical was faulty. They cleaned the EGR valve and for a week or so it was fine. Again its come back, same error. Went back to garage. They've replaced the EGR valve, had it fine for 3/4 days and today on the motorway its come back on. Seems to do it when i'm cruising at the 80mph mark on the motorway and then the car goes into limp mode.

So so far. The car has had replacement turbo and injectors/wiring under warranty. It then had a remap to 200hp and since then i've had it into the garage 2/3 times. They've cleaned the egr/replaced egr/fault cleared But it keeps coming back. They've checcked the turbo for a build on on the vanes, nothing. They have replaced EGR but yet light and limp keeps coming back.

I wondered if anyone here has had a similar issue or knows of anything that could be causing it.
Cheers
Steve