Just bought a P3 Gauge for my S3 8V. The gauge comes with coolant temperature reading as one of the selection which is very good. However I notice the coolant temp display is always above 90C. 105C is what it’s reading from the OBD. For ordinary water temp gauge that comes with the A3, the temp is always 90C after warmed up and it will never go further in normal case. Anyone can explain? My car is brand new with no error code.
Coolant Temp Question
- Thread starter audia38l1
- Start date
The built-in dashboard gauge lies and reports exactly 90 whenever the temperature is anywhere within a range it considers to be "normal". VW group stuff has done this for years, and I think some other makes do too.
Whether the 105 is accurate or normal I can't comment on, but I'm not surprised it tries to tell the truth whilst the dash lies.
There might well be multiple sensors, but the dash computer has a reading it's got from the data bus and then deliberately chooses to display exactly 90 as long as the reading it's got is within what it considers to be normal bounds.
You can see this using VCDS/VagCom. If you connect to Instruments (ie the dashboard computer) and read the coolant temperature value it's an actual, accurate reading. But the dial/text/LED display presented to the user says 90.
Yup. AJB has hit the nail on the head.
The dashboard gauges do not directly measure what is going on with the engine. The dash gauges show a computer simulated value of what the computer thinks the driver wants to see.
Drivers don't like seeing the temperature gauge stabilising at different levels on different days, and this results in customer service calls about possible overheating, when in reality, the temperature is just a bit high because it's a hot day. As a result, once the car has warmed up, the computer simulates a dash reading of exactly 90 degrees.
Only if the computer sees a temperature reading which shows a clear problem (e.g. proper overheating) will it move the needle into the red zone and put on various warning lights/messages.
It's the same with the other gauges too. The tachometer doesn't actually measure the engine speed, at least not during idle. It displays a simulated value of a perfectly flat idle unaffected by stuff like air conditioning and power steering, provided that the engine idle is within the expected normal limits of idle speed for the current operating mode.
The dashboard gauges do not directly measure what is going on with the engine. The dash gauges show a computer simulated value of what the computer thinks the driver wants to see.
Drivers don't like seeing the temperature gauge stabilising at different levels on different days, and this results in customer service calls about possible overheating, when in reality, the temperature is just a bit high because it's a hot day. As a result, once the car has warmed up, the computer simulates a dash reading of exactly 90 degrees.
Only if the computer sees a temperature reading which shows a clear problem (e.g. proper overheating) will it move the needle into the red zone and put on various warning lights/messages.
It's the same with the other gauges too. The tachometer doesn't actually measure the engine speed, at least not during idle. It displays a simulated value of a perfectly flat idle unaffected by stuff like air conditioning and power steering, provided that the engine idle is within the expected normal limits of idle speed for the current operating mode.
