Symptoms:

Intermitent trouble starting the car. Takes 10-15secs of cranking to start engine. Need to pump pedal after it is started to keep it going. Once engine is underway, it runs fine. Occurs a couple times a week.

VAGCOM:

Mileage: 228770km/142151miles
-------------------------------------------------------------------------------
Address 01: Engine Labels: 078-907-551-AHA.LBL
Part No: 4D0 907 551 AH
Component: 2.8L V6/5V MOTR AT D01
Coding: 06252
Shop #: WSC 02324

1 Fault Found:
16500 - Engine Coolant Temp. Sensor (G62): Implausible Signal
P0116 - 35-00 - -
Readiness: 0000 0000

-------------------------------------------------------------------------------
Address 02: Auto Trans Labels: 01V-927-156.LBL
Part No: 4B0 927 156 G
Component: AG5 01V 2.8l5V USA 8509
Coding: 00000
Shop #: WSC 00000

1 Fault Found:
00526 - Brake Light Switch-F
27-00 - Implausible Signal

 

Er, not wanting to be Captain Obvious or anything, but it looks like the coolant temp sensor needs to be replaced, common problem. Brake light signal fault is also very common on a scan and everything is probably fine there.

 

Thanks for reply. I am going to buy the sensor this week , but I thought I would put the codes out there for some feed back. The second code was me hoping for some extra. Thanks again.

EDIT; The dealr will probably know this, but I heard that these cars have two coolant sensors, (one near the thermostat and one on the back of the engine?) any idea which one it is?

 

Your gauge and ECU take their info from the passenger side sensor, two separate thermocouples in one sensor so it can be confusing to diagnose. On the driver's side you will find the sensor for the cooling fan relay. The one to replace it on the passenger side, about $7 at any parts store. Make sure to get a new o-ring too and if you are lucky you will be able to replace without losing much coolant.

 

EDIT; The dealr will probably know this, but I heard that these cars have two coolant sensors, (one near the thermostat and one on the back of the engine?) any idea which one it is?

The one on the back is for the ecm and the gauge. All in one sensor. The other sensor is usually in the lower radiator hose. It checks the cooling system effiecency.

To minimize coolant loss, removed the reservoir cap to relieve pressure and then put cap back on to create a sort of vacuum effect in the system. Youll still lose some but a minimal amount. Also perform change on a cold engine.

 

the one on the back of the engine. PITA to replace so be patient and diligent.
clean out the tube real good, and feel around to make sure there aren't any o-ring filaments sitting around.

 

Replace the one below the intake hose from the airbox to the throttle valve. Takes 15 minutes. No brainer, but make sure your engine is completely cooled and relieve the pressure as dankhound said.

 

Turned out to be really tight around the sensor. Had trouble getting my hand in there and putting the u-clip back on, and I lost a good deal of fluid.

The ECT sensor swap on the 1.8t was much easier!