Warrior193

For clarity, that's for air source heat pumps - but effectively, ground source isn't an option for the majority.

I rather suspect his post was ironic. A significant issue with heat pumps is their maximum attainable outflow temperatures, which will not normally be able to reach the level of a gas or electric boiler. This can cause issues due to radiators now being undersized. Even ground source heat pumps suffer from this unless they use underfloor heating loops.

^^^ But good to test the battery properly to confirm condition before replacing. Simple enough to do while engine is being cranked-over. My understanding is that TDIs are particularly sensitive to slow cranking speeds.

Hello, welcome to the forum. Can you test the battery voltage while the engine is being cranked? Check any earth connection to the engine for tightness and a clean contact.

How much lube oil does your engine consume?

There were some issues with the EA888 series engines, do you know your engine code? I'm guessing you have a late Gen 2 engine. What did a compression test show?

That would seem to be going far into extreme hypermiling territory to the point of stupid if that's what VAG have done! Clear external mirrors are a basic safety requirement - does your heated rear screen behave the same?

Does the Mk4 mirror control rotary selector switch have a mirror heat position? I.e. L; R; Fold and heat.

You say that you are unable to select any gear while the vehicle is moving slowly when this fault shows - what actually happens? does the gear grind/clash as you try to engage it, or does the gear selector just 'baulk' in the neutral position?

It has to be a coincidence - Stop/Start has no connection to physical operation of clutch - just the engine restart switch when clutch pedal is pressed. I'd suggest another check of the master and slave cylinders. Next time this fault occurs stay calm and try pumping the clutch pedal to see if that allows gears to be engaged. You say the clutch has been checked mechanically twice - was the gearbox actually removed for these checks?

When you say ' clutch completely stops working' can you clarify what the clutch pedal does - does it press to the floor with normal resistance, but does not appear to release the clutch plate? When this does occur, does the clutch problem disappear if you pump the clutch pedal?

A post by Guest on June 11 states 'at least 70%'

If you do get the battery replaced, ensure the fitter is able to adapt (code) it to the BCM.

Very likely that your battery is failing.

The alarm integral battery is a backup to prevent it being disabled by simply disconnecting the vehicle battery, but the alarm battery SOC is maintained by the vehicle battery.

It is technically possible to replace the alarm unit integrated battery, but it involves cutting the unit open, then unsoldering the battery from the units PCB - which may possibly be damaged if the battery electrolyte has leaked. Unless confident of skills required for this, probably much easier to simply replace complete unit. AFAIK, the alarm unit is located beneath the wheel-arch liner in one of the front wheel arches (usually drivers side)

If the fault had been due to a slipping clutch, the revs would have increased without the vehicle speed increasing - you do not appear to be saying that this was happening.

With standard CC, the front radar is used only for collision avoidance braking (front assist) and spacing warning when travelling above a certain speed (I think >40MPH) Adaptive CC can be retrofitted, but different hardware needs to be fitted - it isn't just a software update.

What reader devices have previous mechanics used when searching for recorded DTCs? Very suspicious if this fault developed after the cambelt was replaced - but you say incorrect valve timing has definitely been ruled out. From your description and ruling out valve timing error, it sounds as if the turbo boost valve is intermittently sticking open - although I'd have that would light up the EPC warning and put the engine in limp mode.

Does you vehicle have the MFSW ? - On the Mk3, oil temperature can be displayed on the Maxi-dot screen (between the two main dials) by selecting from the function menu.

Does the temperature gauge indicate overheating when this happens? Do you monitor the oil temperature on the maxi-dot screen? Do all the fault indicator lamps show correctly during the self-test before the engine is started? You say 'Timing Chain' in part of your post - and 'Timing belt' in another, do you know which is correct? What is your engine code?

A leaking header tank won't however be causing your emulsified oil issue. Does the engine have regular oil changes?

Good morning, welcome to the forum. Rather than just replacing suspected parts, the first thing you need to do is test the coolant for combustion products and have a compression test done. Your engine code can be found on your V5 document as the first 3 or 4 characters of the engine number.

Your vehicle should have an alarm and the flashing led appears to confirm that it does - it's possible that the alarm unit internal battery has failed, leaking electrolyte onto its circuit board and rendering it US. Try testing it by opening the door while the system is armed.

Thanks, that appears to be Standard (not Adaptive) Cruise Control.