When setting off with a cold engine is OK until I accelerate moderately and the glow plug coil symbol illuminates and the engine goes into limp mode, this is on a 1.6Tdi VAG DBKA engine. If I then stop, turn ignition off and re-start engine the coil symbol is out and all is normal. To cut a long story short the problem is due to a faulty oil pressure sensor especially when the engine is cold.

There are two oil pressure sensors on the engine, 1 for low pressure and one for higher pressure.

The garage diagnosed both sensors were failing, they were replaced and all is back to normal.

The garage ( Non VAG) told me they are getting lots of VAG vehicles with this problem so now keep replacements for both sensors on the shelf.

So double check the oil level manually and if OK get the oil sensors diagnosed and replace but make sure they are OEM grade and not cheaper lool alikes.

 

The sensor with the grey plastic body is the high pressure and the one with the green plastic body is the low pressure sensor.

Hope this is useful to others with a similar problem!

Thank you for the useful info 🙂 glad you got sorted and your A3 is back to normal 🙂

Further to this topic I have some pictures of the two oil pressure sensors which may be of use.

The low pressure sensor (Green body) is part No. 04L919081 pressure range 0.3-0.6 bar.

The high pressure sensor ( Grey body) is part N0. 03N919081 pressure range 2.0 - 2.7 bar.

The low pressure sensor has a very small hole in it's base of approx. 3mm diam so difficult to see inside whereas the high pressure sensors hole is approx. 7mm diam. with a metal gauze protectecting it, this is what gets blocked and stops th sensor working.

It may be possible to clean the gauze on the high pressure sensor and get it working again without spending any money.

These sensors are very common across the range of many VAG group vehicles.