Yeah fill filter with injector cleaner so its nice and strong for a bit, then put the rest of it in your tank. I put mine in 1/4 tank rather than full so it was stronger.
The thermostat is the valve that opens the coolant up to the radiator, if this is stuck open or failed your coolant is open to the radiator all the time resulting in longer warm up, one test is to coast down a long downhill when its cold outside and see if your temp gauge drops.

Also did you use a genuine temp sender? The sensor has 2 sensors in it, one for ecu and one for dash
 
I've not replaced the temp sender yet. The readings on vagcom matched the dash.

A few weeks back I noticed it would get up to temp then drop down to nearly quarter temp. So that makes sense. My radiator fans don't work either. But that's because it keeps blowing the fuse due to the notorious fan issue :(
 
Ok, so an update on this...

I've replaced the thermostat and the fuel filter (as it looks like it was an original).

The car now starts and runs fine when cold, however, the temperature on the dash is still drops back down when the car is sat in traffic before it has fully warmed up. I don't know if there is any air in the system, but we certainly spend long enough getting it out!

Any ideas? Because of this, my car is still averaging about 40mpg. :(
 
Have you got the interior fans on heating? I found mine dropped slightly as the interior fans are drawing cold air in over the heater matrix, as diesels dont produce loads of heat, the cold air for the interior heater was actually cooling the engine down, once turned heaters off the engine warmed up.
Its so cold at the minute it will take a while to warm up, especially if you are running interior heater.
 
We bled it by taking the pipes off the T bit near the expansion tank and blowing into the tank so water came out of the pipe and did that for about 5 minutes and about 6-7 litres of water...

I had to have the heat on as my windowscreen kept misting up!

It did it every time I slowed down or stopped. About 3 times, it'd just get up towards 90 then drop down to about 75 :(
 
May wanna just remove expansion tank lid, put heaters on max temp and wait till it heats up :)
 
Iv allways understood they are self bleeding, fill it slowly and run engine with cap off, go for a drive and check the level.

Can you set the heater to low so your only blowing fresh air, but wear a coat. Just to see if that helps.
 
Thanks for the advice guys. Car is now bled. Seems to be ok. Fuel economy is still a bit down though. :(
 
I would agree with the above I replaced thermostat as I had same temp needle dropping issues, fault remained replaced coolant temp sensor issue resolved

D.
 
Vagcom's not showing any errors with it and the readings seem to be spot on with it... :(

But for the sake of about £20, why not :)
 
I'm taking the car in to a garage tomorrow to get them to check this over, haven't had chance to change the CTS, but the issues seems to be when the climate control kicks in, the temperature drops down and then stays down for ages, which I've never witnessed on any car ever... :O
 
Hey, super extended resurrection on this thread... But, update!

I changed the CTS, still the same kind of issues, noticed now that the temp gauge takes ages to start reading anything but the ECU side (on the climate control trick), reads 90 within about 10-15 minutes of driving at ~70mph.

I've checked with VCDS and after 45 minutes of driving the temp gauge and VCDS both measured 74c (climate control still read 90).

I've checked the wiring to the sensor and one side reads 5v but the other side only reads 1.18v... I've also got fault code http://www.obd-codes.com/p0118 which says it could be wiring.

Any ideas where I should be checking?

Any ideas appreciated as the car has had a turbo and then the clutch go within 6 months so I'm getting pretty fed up (and skint) now.

Thanks again!
 
Why would a faulty stat cause the ECU and gauges to read two different readings? I think it's wiring but I wouldn't know where to start. :(
 
Dash reads higher than ecu always, it's a vag thing.

If the ecu temp doesn't reach 90c then the thermostat is not functioning correctly and staying open causing the lower temperature.

Your probably experiencing a slow warm up aswell but not noticed as it's a gradual failure.

Ecu temp is correct figure to use for diagnosing from.
 
When my stat went a couple of years ago it was slower than this to warm up and the temp would drop again. It hits 90 on the ECU and stays there. On the gauge it take over 40 minutes to start moving and never goes over 75c. :(