Blue Temp Sender - What It does & How To Reset The ECU After Fitting (8V Digi)

[X4MGS]

Blue Temp Sender

Can't take the credit for this - but I think its worth posting in here so peeps know what it does and how to reset the ECU after you have fitted a new one!

I would also suggest that you ONLY fit Genuine VW/VAG one's - They don't cost that much more than copy ones but do seem to last longer & what you save in the sender cost you can lose in fuel consumption when it stops working!!!!!

Stolen from wikipedia  

Most of driveability issues can be traced back to a few issues:
Bad ECM earth/ground
Bad o2/lambda sensor earth/ground
Faulty Engine Coolant Temperature sensor (ECT/MFTS)

• The engine coolant temperature sensor is located in the coolant flange,(under the distributor on the Polo Fox Coupe) on the front of the cylinder head (on transverse-engine vehicles).
• The bad earth/ground can be traced to an essential ground/earth strap on the front upper transmission (Gearbox) bolt. Without this, the ECU tends to earth/ground elsewhere, causing a specific trace to burn out on the circuit board and killing the ECU. This causes the injectors to stay open constantly, flooding the engine.
  

Digifant engine management; Common issues that are indicative of a failed ECT/MFTS (Temp Sender) are:

• Vehicle idles poorly
• Engine sputters, might stall
• Higher than normal fuel consumption

The part number for this sensor is '025 906 041 A' (always check with your Volkswagen dealer for the most updated part number).
The resistance of this unit is appriximately 3.2 Kohm at 10 degrees C.
If it measures open circuit this will explain erratic idle and throttle speeds especially when the engine is cold.


When replacing this sensor, it is important to also replace the O-ring ('N 903 168 02').

Once the new sensor has been installed, start the engine and disconnect the blue coolant temperature sensor.
Rev the engine through 3,000 rpm three times, each time allowing the throttle to close completely.
This clears the Digifant ECM fault memory.

[X4MGS]

Blue temp sender can be tested by running the car and then unplugging it on tickover and you should hear the engine start to run erratically...

[siddleg]

cheers fir that bud ill give it a go

[vii-cks]

Can anyone please advise when you unplug it after fitting should the engine completely stall after poor running or should it remain running but just rough. Ours seems to cut out each time after I've changed it on my partners mk2.

[Steve_B]

Can also be tested by measuring resistance across the pins, as long as you know the temp. Link will show expected values:

http://vnc.thewpp.ca/stuff/bentley/ep0niks.ctech.ca/vw/eva2/FU01/ch7.2.1.html

[apie2004]

Does anyone know what the part number is of the older version of this sender which is threaded and white?