nige8021

Under the bonnet on passenger side on the rear bulkhead

This guy might have something ? https://www.ebay.co.uk/itm/303710143089?hash=item46b6890271:g:2WYAAOSwIKlfXx31

I know that feeling, you could try from the ABS unit connector, left front pins 8 & 9, right front pins 5 & 6, left rear pins 3 & 2, right rear pins 11 & 12 "B" is looking into the connector

Have you compared the other three sensors to see what sort of value they are giving ?

@Graham Butcher when the sensor failed on my 13 plate Treg it was open circuit or greater than 20Mohms (largest range on meter) the replacement (and I think it's the same part as on your Octy) was 1.2Kohm,s also just tested a used & new sensor for a MK1 Octy and they are 990ohms & 1.1kohms respectively

As I said before the CTS has no control over the radiator fans, they are controlled by a thermal switch on the radiator, you can easily test the system by shorting the pins on the thermal switch together, if that proves the fan/s are OK then either the thermal switch is goosed or the water passing the switch isn't getting hot enough and that could be a stuck thermostat, or the waterpump isn't circulating the water but I seem to recall you saying the gauge did read 90c ?

What sort of scanner was it ? as it probably would not respond to a generic OBDll reader ideally needs to be a VAG specific and even better VCDS

I think what @J.R. was referring to that the engine ECU on some models also stores the mileage separate to the displayed mileage in the speedo and what you have posted

As the airbag ecu has detected a fault you will need the correct diagnostic kit to turn the light off and kit will direct you to the cause of the problem, common problems are the connectors under the driver/passenger seats with the passenger most common as that tends to get moved back/forwards more than the drivers unless there are lots of different drivers ?

Don't McD's claim their delivery fleet is run on the used oil ? so I wouldn't count on them for any cheap/free oil

@nta16 I also saw the evidence when I converted a petrol speedo to diesel for my old mk1 Octy to do this I had the download the eeprom data and put the diesel tacho figures into the petrol eeprom and I plotted the input/ouput of the other gauges using a XLS file converter and you could see the plateau on the temperature input to output so I did a bit of reverse plotting to have the plateau removed

I was 2c out in my original comment but that was just going off a failing memory, the pic below is from ElsaWin a copy of the stealers workshop manuals

I used it on my Touareg a while ago and it worked great,

That's how the OEM glowplugs are connected up

Well that doesn't sound like you have the correct part then, if the one on the car has 2 wires but your replacement has 4 ???

Black/Purple wire on pin 14 of the 16 pin connector on the control unit is an ignition ON supply from fuse #9

The gauge reads 90c for an actual coolant temp between 75~105c

You could run a wire to the fusebox and piggyback off any ignition ON supply, just the AC controller is just below the radio so only a short bit of wire required, so do you have climatic or climatonic ? then I can tell you what wire to piggyback from

I wish CH4 would drop that idiot presenter Jones, he's embarrassing to listen to when he attempts to interview anyone, it was such a pleasure to have Lee McKenzie last time out in Saudi as lead presenter, she is a professional interviewer who knows the right questions to ask

The OEM radio will of used the CANbus system to switch the radio on/off so there isn't an ignition ON supply at the radio connector, if you have AC (climatic or climatronic) ? there is an Ignition ON supply to the control/display unit that you could piggyback off to control the radio

It's an improvement over the supplied "widow maker" but not by much, as said above a good trolley jack is the safest option

Does the water temp gauge indicate 90c when it's been running for a while ? if it does then the CTS is doing it's job correctly, as in that bit you have posted, check the live data with a stone cold engine and see if it's at or around ambient temp if it's reading silly low or high then it will affect the engine at start up as the ECU will think the engine is really cold or hot and adjust the fuelling schedule to suit

The CTS has nothing to do with the radiator fans they are controlled by a thermal switch on the radiator Clean throttle valve control unit -J338- Note t If a new engine control unit is fitted, the throttle valve control unit -J338- must be adapted. The adaptation must only be carried out with a new or cleaned throttle valve control unit -J338-. Dirt/carbon deposits in the end stop of the throttle valve can lead to incorrect adaptation values. t The throttle valve support must not be scratched when cleaning. – Remove air filter housing: t Engine identification characters AUA, AUB, BBY, BKY, BBZ t Engine identification characters BUD – Remove throttle valve control unit -J338- – Open the throttle valve manually and block the throttle valve in the opened position with a suitable object (e.g. plastic or wooden wedge) WARNING Acetone is easily inflammable. Observe the accident prevention regulations and the safety instructions when handling easily inflammable fluids. Do not use compressed air when cleaning the throttle valve. Wear safety goggles and safety clothing, in order to avoid injuries and skin contact with fuel. – Thoroughly clean the throttle valve support, in particular the area of the closed throttle valve , with commercially available acetone in accordance with DIN 53247 and a paint brush. – Wipe the throttle valve support with a fluffy cloth. – Let the acetone dry off completely and re-install the cleaned throttle valve control unit -J338-. – Adapting the engine control unit to the throttle valve control unit -J338- → Vehicle diagnostic, testing and information system VAS 5051.

https://www.autoglym.com/products/bodywork/magma this is safe to use on bodywork

Check the wiring inside the flexy rubber conduit between the door and frame