The Reducer Level Sensor (RTS) is used on diesel exhaust vehicles, and its function is to communicate electronically to the Engine Control Module (ECM) the fluid levels in the DEF (Diesel Exhaust Fluid) storage tank. To make this reading, this sensor uses 3 stainless steel pins, in which the length between each one indicates the different levels in the tank. Also, there is a fourth pin, which is used as a ground pin.
When the Diesel Exhaust Fluid remains in the storage tank below the DEF levels set by the vehicle manufacturer, the Engine Control Module will determine that it is too low, which will cause the P203F OBDII fault code to be set.
The reasons for the DTC P203F OBD2 being stored are:
Electrical components related to the Reducer Level Sensor may be bad.
Diesel Exhaust Fluid may not be adequate.
DEF levels could be excessively low.
The reductant Level Sensor may be defective.
Possible solutions of the DTC code P203F Generic
Perform the following steps to troubleshoot the P203F OBDII diagnostic code:
Consult the Technical Service Bulletins (TSB) according to the year and make of your vehicle.
Check that the electrical components associated with the Level Reducer Sensor are not damaged. If you observe burnt wires or high levels of corrosion on the sensor connector, you should make the necessary repairs.
Verify that the Diesel Exhaust Fluid level in the storage tank meets the required levels. Also, check that it is not contaminated. Corrects it as required.
Using a multimeter performs resistance tests on the Level Reducer Sensor. Compares the results obtained with the values specified in the service manuals. If you get data that differs from the set values, it is due to a bad sensor, replace it.