Replacement value for coolant temperature sensor (CTS) when disconnected

"When I disconnect the sensor, VCDS displays a value in column 4 of row 7 in the Measurement Control module."
which surprisingly corresponds exactly to the value of the fuel temperature.
It matches (the ambient temperature was around 20°, and the intake air temperature was 13°).
Actually, I was expecting a much lower value because you can achieve this with...
Removing the sensor is said to sometimes cause a start-up issue.
can simulate very low temperatures.
Does anyone know what's going on?

Best regards, Klaus.

Klausel wrote:

When I disconnect the sensor, VCDS shows a value in module control (MWB) column 4, row 7. which surprisingly corresponds exactly to the value of the fuel temperature. It matches (the ambient temperature was around 20°, and the intake air temperature was 13°). Actually, I was expecting a much lower value because you can achieve this with... Removing the sensor is said to sometimes help with starting the engine. can simulate very low temperatures. Does anyone know what's going on? Greetings Klaus

.
Hello,

If a sensor fails and is detected as defective, the engine control unit attempts to use an appropriate substitute value, depending on the software version (meaning the behavior may not always be consistent).
In your case with the AFN engine, it's the fuel temperature sensor, which makes sense given the temperature conditions during engine start-up.

It is still advisable to replace the coolant temperature sensor as soon as possible, because otherwise various parameters, such as the injection timing, may no longer be accurate.

Best regards, Rainer.

Hi there,
The 1Z engine supports both functions: providing a substitute value for the temperature (fuel temperature) and enabling extreme cold start conditions with extended preheating when "ignition is on." This may also apply to the AFN engine.
That all makes sense. In the event of a failure in the coolant temperature sensor, the engine control unit (ECU) can at least provide limited regulation, the auxiliary heater only operates according to the "coolant temperature" reading, and cold starting with preheating still functions.
hg
Herbert.