P203F — Toyota Code

This is significant because, in the majority of cases, reductant level sensors are found on diesel-powered vehicles that have a DEF (Diesel Exhaust Fluid) storage tank. One of the main objectives of the ECM, as previously indicated, is to reduce overall vehicle emissions. DEF, a urea solution, is used in diesel engines to help with exhaust burning. The ECM receives information about the level of DEF fluid in its storage tank via the reductant level sensor.