This screen allows you to calibrate the Coolant Temperature (CLT) or Intake Air Temperature (IAT) sensor to ensure the ECU reads accurate temperature values from standard or custom thermistors.
The interface and logic for both CLT and IAT sensors are identical, and only the sensor input assignment changes.
Many automotive thermistors (NTC sensors) vary resistance or voltage with temperature. Since different sensor types have unique curves, calibration ensures:
| Voltage (V) | Temperature (°C) |
|---|---|
| 0.393 | 130.0 |
| 2.162 | 60.0 |
| 4.947 | -40.0 |
Live readings shown on the right side of the interface:
Used for real-time validation of your calibration.
| Field | Description |
|---|---|
| Max Value | Upper voltage limit accepted from the sensor |
| Min Value | Lower voltage limit accepted from the sensor |
| Default Temp | Fallback temp if the sensor is not detected (e.g. open) |
These define safe input voltage bounds to avoid misreadings due to open circuits or shorted sensors, when out of this range a DTC will be triggered.
The Quick Cal button offers pre-configured calibrations for many commonly used sensors (e.g., Bosch, GM, Honda, Toyota). It provides:
🧠 If your sensor is not listed, you can manually calibrate using the procedure below.
If using a custom or unknown sensor, follow this process:
Select three temperature points, ideally:
Measure voltage or resistance of the sensor at those points
Enter the values into the table
Vout = (Vsupply * Rsensor) / (Rsensor + Rpullup)
The pullup on the RM-Primis is 1Kohm
4. Enable the sensor
| Button | Function |
|---|---|
| Load | Loads a saved calibration table |
| Store | Saves the current table to flash |
| Import Table | Import sensor data from file |
| Quick Cal | Load a known sensor preset |
| % Correction | Adjust table globally for fine tuning |
| Parameter | CLT Calibration | IAT Calibration |
|---|---|---|
| Sensor Enabled | ✅ Checkbox | ✅ Identical UI |
| Table Format | Voltage vs Temp | Voltage vs Temp |
| Live Monitor | Shows real-time Voltage + Temp | Shows real-time Voltage + Temp |
| Default Usage | Warm-up, fans, timing, fueling | Spark, fueling, intake efficiency |