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Discussion Starter · #1 ·
Hi,
I have an 1.0 Twinport Z10XEP in which i changed the thermostat today. Reading the temperature through the obd port shows normal 90-92 degrees C. My problem is that the Dashboard gauge shows something like 86-88 degrees c. Its like the dashboard gauge has an offset.

Any suggestions?
 

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It is possible that the ecu measures from another point of the cylinder head, or even based on the oil, anyway if you suspect the indicator, locate it, and with the ignition on, unplug it and tap the connector, if both are put at the same maximum temperature I would not worry, as the ecu measures the thermo contact of the radiator
 

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Discussion Starter · #5 · (Edited)
The ECU and gauge both use the same temperature sender on your model which is in the top of the water pump.
I would say at some point your dials have been apart and the needle been put back on in wrong place slightly as they are just a push fit on the spindles with no key.
That is really helpful! Thank you mate!
So I just need to take apart the dashboard and try to get it in the right position. Is there any reference for the right position or just trial and error?

Edit: Does we know how the temp sensor works? Maybe I can trick it to show 90 degrees and then place it there! Works with resistant, analog voltage, analog current or some digital protocol? I am electrical engineer so it is easy for me to make a circuit and trick it if i know what the temperature sensor outputs.

Edit 2: Now i am wondering why they removed the needles. Maybe they tamper with the mileage. SAAADDDD
 

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It could be some one swapped the dial faces from black to white at some point? Or that the dials have been swapped?
The mileage can be reprogrammed with Tech2 but not sure about Opcom? But I think the true mileage can be stored in the BCM as well as the dials or it may be one of the other controllers? I know I found 2 different mileages in my Corsa C sri which has had 4 engine swaps in it's life and new ECU's each time along with a new BCM. The dials in mine are the true mileage for the shell for mine as I know it's history before I got it.

Glad it's sorted and fast. You know your way around electronics. (y)
The data from the temp sensor is transmitted to the ECU then vis the canbus to the dash.
 

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Same with my Meriva diesel, the gauge consistently under reads but if you look at the temperature via OpCom it is higher. Only way to know which is correct is to slave in a known calibrated sensor to a calibrated gauge. To be honest it doesn't bother me enough to mess with it.
 

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Discussion Starter · #9 ·
It could be some one swapped the dial faces from black to white at some point? Or that the dials have been swapped?
The mileage can be reprogrammed with Tech2 but not sure about Opcom? But I think the true mileage can be stored in the BCM as well as the dials or it may be one of the other controllers? I know I found 2 different mileages in my Corsa C sri which has had 4 engine swaps in it's life and new ECU's each time along with a new BCM. The dials in mine are the true mileage for the shell for mine as I know it's history before I got it.

Glad it's sorted and fast. You know your way around electronics. (y)
The data from the temp sensor is transmitted to the ECU then vis the canbus to the dash.
I hope it is something like that for the dash. Some day I will ask from a local mechanic to check the millage if I ever go to one (I am doing every maintenance my self for now, and a Haynes manual is on the way).

Yes I sorted it out fast because of holidays and your help. I Really thank you! 🤝
 

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Discussion Starter · #10 ·
Same with my Meriva diesel, the gauge consistently under reads but if you look at the temperature via OpCom it is higher. Only way to know which is correct is to slave in a known calibrated sensor to a calibrated gauge. To be honest it doesn't bother me enough to mess with it.
The temperature sensor I don't think it brakes regularly because it is just a thermistor. For the temp sensor I know it is working because I just fitted a new thermostat (after flashing the cooling system and placed new antifreeze afterwords) and the ECU posts 90-92 degrees C witch is bang on with the temperature spec of the thermistor (92 degrees).

The gauge it is now accurate at all. I checked it today and for 110 degrees after I removed the offset it shows 100 degrees. So it is only good to see if the temp goes above 90, or stays below 90 and then start searching.

Really it is not to much work to disassemble the dash, it took me about 5-10 minutes i think.
 
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