Head gasket perhaps?

[maddogphysics]

Passat 06 reg 170 version.
Recently, last 6 months, started losing some coolant, and now losing a couple of litres per week.

Have noticed white clouds when engine is cold but this disappears after it has warmed up.
Can't see any leaks in the engine, or evidence of leaks.
Oil from dipstick is normal.
Have replaced expansion cap but this has made no difference.
Water level in expansion bottle remains fairly level with cap off and engine on.
System stays pressurised when engine left to cool down for a day or so.

Engine light and coil now on and give the following codes:
Address 01: Engine Labels: Redir Fail!
Part No SW: 03G 906 018 AS HW: 03G 906 018 AS
Component: R4 2.0l PPD1.2 G 9925
Revision: --H22--- Serial number: VWZCZ000000000
Coding: 0000072
Shop #: WSC 00199 210 83391
2 Faults Found:
001137 - Exhaust Pressure Sensor 1 (G450): Implausible Signal
P0471 - 006 - Short to Plus - Intermittent
Freeze Frame:
Fault Status: 00000001
Fault Priority: 1
Fault Frequency: 8
Reset counter: 40
Mileage: 188723 km
Time Indication: 0
Date: 2000.00.00
Time: 14:16:00
Freeze Frame:
RPM: 0 /min
Torque: 144.0 Nm
Speed: 0.0 km/h
Pressure: 63.9 mbar
Text: -42
Text: mbar
Text:
001137 - Exhaust Pressure Sensor 1 (G450): Implausible Signal
P0471 - 006 - Short to Plus - Intermittent
Freeze Frame:
Fault Status: 00000001
Fault Priority: 1
Fault Frequency: 8
Reset counter: 40
Mileage: 188723 km
Time Indication: 0
Date: 2000.00.00
Time: 14:16:01
Freeze Frame:
RPM: 0 /min
Torque: 144.0 Nm
Speed: 0.0 km/h
Pressure: 63.9 mbar
Text: 340 C
Text:
Text:


and

Address 01: Engine Labels: Redir Fail!
Part No SW: 03G 906 018 AS HW: 03G 906 018 AS
Component: R4 2.0l PPD1.2 G 9925
Revision: --H22--- Serial number: VWZCZ000000000
Coding: 0000072
Shop #: WSC 00199 210 83391
1 Fault Found:
001350 - Sensor 1 for Exhaust Temp Bank 1 (G235): Short to Plus
P0546 - 006 - Short to Plus - Intermittent
Freeze Frame:
Fault Status: 00000001
Fault Priority: 5
Fault Frequency: 46
Reset counter: 40
Mileage: 189830 km
Time Indication: 0
Date: 2000.00.00
Time: 14:30:02
Freeze Frame:
RPM: 2016 /min
Torque: 88.0 Nm
Speed: 0.0 km/h
0.00 %
Voltage: 14.13 V
Temperature: 17.0°C
Text: 1000 C



stumped about problem.
Ideas anyone?
Thanks

[maddogphysics]

Update to the problem.

Seems it was the EGR cooler that was at fault.
Had a new one put in and the coolant leak disappeared as did the white smoke.

The EGR cooler is attached to the exhaust so when the car is first started, the exhaust gasses heat up the coolant so the engine warms up more quickly.
It appears this is a common fault if you have a coolant leak and can't see where it's coming from.
VW quoted £751 inc. Vat.
£391 fitted inc. VAT by Volks-Tek in Dronfield near Sheffield with genuine VW parts. Thank you.

The other codes indicate I need an exhaust gas pressure sensor. (£101 from Volks-Tek, £350 from VW)