Temperature Gauge under reading

[Natastrophe]

I've seen a lot of threads on here on this subject, but am not sure as to the cause of the issue.

Basically, if I idle my car, it warms up to an indicated 90C and sits there. The problems start when I drive.

Around 30mph, 90C is still reading, my obs2 reader says around 80C

As speed increases, temperature drops, so the dial may indicate 70C at 70mph, the obd2 reader reads around 60C

Slow down and the temperature returns to 90C

However, I did more testing today, and I think the fan is not cutting in, I cant hear it.

I let the car idle and the temperature rose to 102C on the obd2 reader, yet the cars own gauge was stuck on 90C

This happened about 3 weeks ago and the aircon packed up at the same time. related?

What temperature does the fan kick in? I'm guessing if the sensor is broken, it may not function as it should?

So far, I've been told it could be

1. The water pump
2. Using E90 fuel
3. The radiator fan resistor
4. The Temperature Sensor/Thermistor
5. The Temperature Sensor & Housing

Has anyone successfully diagnosed this, and ideally I want to keep costs down.

Thanks
Natalie

 

[RCZ-mad]

I've seen a lot of threads on here on this subject, but am not sure as to the cause of the issue.

Basically, if I idle my car, it warms up to an indicated 90C and sits there. The problems start when I drive.

Around 30mph, 90C is still reading, my obs2 reader says around 80C

As speed increases, temperature drops, so the dial may indicate 70C at 70mph, the obd2 reader reads around 60C

Slow down and the temperature returns to 90C

However, I did more testing today, and I think the fan is not cutting in, I cant hear it.

I let the car idle and the temperature rose to 102C on the obd2 reader, yet the cars own gauge was stuck on 90C

This happened about 3 weeks ago and the aircon packed up at the same time. related?

What temperature does the fan kick in? I'm guessing if the sensor is broken, it may not function as it should?

So far, I've been told it could be

1. The water pump
2. Using E90 fuel
3. The radiator fan resistor
4. The Temperature Sensor/Thermistor
5. The Temperature Sensor & Housing

Has anyone successfully diagnosed this, and ideally I want to keep costs down.

Thanks
Natalie

Definitely get the temp sensor changed before you do anything else, it's a relatively cheap part, easy to replace and almost certain that is the issue.

 

[Pedro]

Check the heater is working normally then Aircon if OK then consider changing the Thermostat tank as these are electronicky controlled & if your Air con is disabled then this is the reason why & the Temp is in range if at 90-105 the fan is triggered by the ECU for temp faults you could check the fan resister for any issues but when the gauge show any drop or rise its poss the the thermostat is failing mine has had 2 new ones in the last 12000 KLms