Climatronic Diagnosis: Troubleshooting & Repair

Hello everyone!
The engine temperature described in section 45 of this diagnostic mode: does this refer to the coolant temperature or the oil temperature? It would be very useful to know when the oil has reached its operating temperature.
best regards, markus

This is the coolant temperature reading from sensor G71. It's located on the cylinder head, directly next to the glow plug auxiliary heater.

Regards,

Manuel.

Hi!

I suspect that this value is merely calculated for the climate control system. In my A3, manufactured in 1999, after turning on the ignition and the engine is off, the temperature reading increases to exactly 90 degrees.
It definitely isn't the oil temperature.

Best regards,
Uwe.

When the intake air temperature drops below 5 degrees Celsius, this glow plug heating system activates. That's why you're seeing an increase in the temperature reading.

Is that channel 48 on your A3, right?

Regards,

Manuel.

Hi!

I tried it again this morning.

A3 AHF, ambient temperature 12 degrees, channel 51, temperature reading increasing.
A4 AJM, located next to it, temperature is not increasing!
What kind of glow plug heating system is this? Could something be heating up in my A3 even at higher outside temperatures?

Best regards,
Uwe

This glow plug heater is located exactly where the temperature sensor is also situated.

The temperature sensor G72 reports the temperature in the intake manifold to the control unit after the ignition is turned on. When a certain threshold (approximately 5 degrees Celsius) is reached, the glow plugs in the coolant are activated.
To prevent the battery from discharging, one, two, or all three glow plugs are activated, depending on the capacity of the three-phase generator. The three-phase generator is connected to the control unit via the DF terminal. When the engine is not running, only one glow plug is used for heating.
The auxiliary heater will be switched off when the coolant reaches a certain temperature. The rule is: the colder it is, the longer the coolant will be heated.

Regards,

Manuel.

Hi Manuel!

You probably mean the glow plug heater, at least that's what I call it in my vocabulary. Sorry, the glow plug heater terminology confused me a bit.
Okay, I tried something: I kept the ignition on for 20 minutes without starting the engine. On channel 51 (engine temperature), the display slowly rises to 90 degrees and then stops exactly there, as if stuck. This display doesn't correspond to the analog coolant temperature gauge, which remains at the bottom. The ventilation fan tries to heat the interior and goes up about 7 levels. It's probably just calculating the value instead of actually measuring it...

Best regards,
Uwe.