Water Temperature Sensors: Location on ASZ Unit.

Hello,

I am gradually exploring and learning about my PD motor.

I've now found the combination sensor for boost pressure and air temperature, as well as the diesel temperature sensor. Today, I happened to find a coolant temperature sensor.

In the wiring diagram for the AXR/ATD engine in the Polo 9N, the G62 sensor is indicated for the EDC (Electronic Diesel Control) system. However, in the wiring diagram for the base model, there is no sensor for the water temperature that connects to the instrument cluster (unlike the VP engines, which have a dual sensor for both EDC and the instrument cluster).

When I tested the found water pump with a resistance of 330 ohms while the engine was cold, the temperature gauge showed 90° when the ignition was turned on.

There wasn't time for a full VAGCOM diagnostic scan, so here's a quick question for everyone:

Are only one sensor used for the coolant temperature in newer engines, and is the measured temperature then transmitted via CAN to all control units that need the information?

Hello Ulf, in your case, that might be true, but there are also engines that have multiple sensors for coolant temperature. For example, the function of the radiator fan is monitored in this way.
But that's probably not the case with diesel engines.
Is your power supply two-pin or four-pin?

@ulf

Okay, I can only speak from my experience with my PD (ATJ with 115 hp), which has two sensors in one housing (one goes to the instrument cluster and one to the control unit). However, the sensor for the instrument cluster seems to be defective, as the instrument cluster is displaying an error indicating that the sensor is either open or shorted to B+.

Best regards, WarLord.

mersente wrote:

Hello Ulf, in your case, that might be true, but there are also engines that have multiple sensors for coolant temperature. For example, the function of the radiator fan is monitored, but this is probably less common in diesel engines. Is your power supply two-pole or four-pole?

Hi,

The valve is 2-pole, unlike the (water) double valves that I am familiar with, which are 4-pole.

I actually had some time today to connect the VAGCOM device and use a hot air gun to heat up the various sensors (in order to, among other things, verify the association of the measurement value fields in my label file).
The water temperature sensor, which shows a reading of 90° when measured with a 330 Ohm resistor, also causes one of the temperature fields in the VAGCOM diagnostic tool to increase when the engine is warmed up.
According to this, this single power supply apparently provides power to the EDC and the AI.

Thank you for your responses!