Fluctuations in the temperature display on the G4 AXR

Hi everyone,

The temperature gauge on our G4 TDI (AXR, 74kW, year 2001) occasionally fluctuates. Within 1-2 seconds, the reading drops to the cold range or just above it, then recovers slightly, remains low (around 1/4 to 1/3), or sometimes returns to normal.

It initially sounds like a faulty temperature sensor. Since the car was in the workshop due to accident damage, the 'temperature sensor' was replaced as part of the repair. However, the display problem is not related to the accident damage.

Unfortunately, the problem was not resolved by simply replacing the sensor. The fluctuations are still occurring.

Some engines are obviously equipped with two sensors (1x KI, 1x MSG). What about the AXR engine? Did the workshop perhaps replace the 'wrong' sensor? Where is the temperature gauge sensor located?

I would be grateful for any suggestions or tips.

Best regards,

Eike.

eike wrote:

Some engines are obviously equipped with two sensors (1x KI, 1x MSG). What about the AXR engine? Did the workshop perhaps replace the "wrong" sensor? Where is the temperature gauge sensor located?

The AXR is a dual-temperature sensor. This means it has two sensors in one housing, with four connections. Therefore, the wrong sensor could not have been replaced. It seems there's likely an issue with the wiring.

Hello,

Thanks for the information. Where is the sensor located?

Here's another peculiarity: when you turn the ignition on without starting the engine, you can hear a kind of whistling sound coming from the engine compartment. The volume is similar to the warning light indicator, but the tone is much higher. It's difficult to pinpoint the exact location acoustically, but it sounds like it's coming from the area around the cylinder head. However, that could be misleading.

Does anyone know about this and what the cause might be? Could there possibly be a connection to the display issue?

Thank you and greetings.

Eike.

eike wrote:

Where is the sensor located?

Beneath the tandem pump is a large water flange, which also houses the three glow plugs. The temperature sensor is installed in this flange from the rear. You just need to feel around to find it; you can hardly see it.

Regarding the sound: I have no idea what it is; I've never heard anything like it before. Could you record it for me?

Hello,

Thanks for the information. Where is the sensor located?


From the back, access to/of the control panel. Discreetly accessible.


There's another peculiarity: when you turn the ignition on without starting the engine, you can hear a kind of whistling sound coming from the engine compartment.

Does anyone know about this and what the cause might be?


Yes.


Is there perhaps a connection to the display issue?


Definitely not!

Only when the sound is missing would I start to worry .

The noise is coming from the DK (likely a device or component). It's electrically controlled by the AXR and powered with a voltage that is modulated using Pulse Width Modulation (PWM). Under certain conditions, this can be heard as a whistling sound.