Technical Description of OBD-II Trouble Code
Intermittent/Erratic Circuit for Reductant Level Sensor
What does that signify?
This is a generic diagnostic trouble code (DTC) for powertrain issues and is commonly found in OBD-II vehicles. This code can apply to various vehicle makes such as BMW, Mercedes Benz, VW Volkswagen, Sprinter, Ford, Audi, Dodge, Ram, GMC, Chevrolet, Jeep, etc.
Were you aware that the engine light illuminates when the engine’s exhaust emissions do not meet the specified standards? The ECM (Engine control module) monitors and adjusts numerous sensors, valves, systems, etc. Essentially, it functions as an integrated emissions testing station. It not only monitors the intake of your engine but, more importantly to the manufacturer, it monitors what your engine emits into the atmosphere.
This is relevant in the context of reductant level sensors, which are primarily found in diesel-powered vehicles with a DEF (Diesel exhaust fluid) storage tank. DEF is a urea solution used in diesel engines to assist in burning exhaust, thereby reducing overall vehicle emissions. As mentioned earlier, this is one of the ECM’s most important functions. The reductant level sensor communicates the DEF fluid level in its storage tank to the ECM.
P203E is the trouble code defined as “Reductant Level Sensor Circuit Intermittent/Erratic” and indicates that the ECM has detected an erratic or intermittent electrical reading from the sensor circuit.
A reductant DEF tank:
What is the severity of this DTC?
Considering the possibilities, I would classify this as a relatively minor code. Essentially, it indicates a fault in a system that monitors what happens after the exhaust has been burned and used. However, most states/countries have strict emissions standards, so it is advisable to address this issue before it causes further harm to your vehicle and the environment!
What are some of the symptoms of the code?
The symptoms associated with a P203E diagnostic code may include:
What are some of the common causes of the code?
The causes of this P203E engine code may include:
What are some P203E diagnostic and troubleshooting steps?
The first step in troubleshooting any malfunction is to refer to the Technical Service Bulletins (TSB) for known issues with your specific vehicle.
Advanced diagnostic steps are highly vehicle-specific and may require specialized equipment and knowledge for accurate performance. However, we have provided some basic steps below. For specific steps tailored to your vehicle’s year, make, model, and powertrain, please consult a vehicle-specific repair guide.
Basic Step #1
Before diagnosing any present codes, ensure that all active codes have been completely cleared and test drive the vehicle. This will clear any codes that may have remained active after repairs or other intermittent, less significant codes. After the test drive, rescan the vehicle and proceed with diagnosing only the active codes.
Basic Step #2
If you have owned your vehicle for a significant period of time, you are likely familiar with the location of the DEF (Diesel exhaust fluid) storage tank. If not, these tanks are typically located in the trunk or under the vehicle. The filler neck for the storage tank should be easily accessible, either in the trunk or next to the fuel filler neck. Prioritize identifying the correct tank to avoid placing fluid in the wrong location. If you can mechanically check the fluid level with a dipstick, do so. However, some vehicles do not have a way to verify the DEF level other than visually inspecting the tank with a flashlight. Regardless, it is important to top up the fluid, especially if P203F is present.
Basic Step #3
If your OBD2 code reader/scan tool allows for it, you may be able to electronically monitor the sensor. This is particularly useful if you know that the storage tank is full of DEF and the reading indicates otherwise. In such cases, it is likely that the reductant level sensor is defective and needs to be replaced. However, replacing the sensor can be challenging as it is mounted to the tank. Take precautions to catch any DEF that may spill when replacing the sensor.
Basic Step #4
If you can easily access the connector for the reductant level sensor, ensure that it is making a secure electrical connection. Additionally, consult the manufacturer’s service data for specific values and procedures to test the level sensor and confirm its defectiveness before replacing it. You will likely need a multimeter for this, as resistance tests may be involved. Compare the actual values to the desired ones provided by the manufacturer. If the values deviate from the specifications, the sensor will need to be replaced.
NOTE: Always follow the manufacturer’s guidelines regarding when to disconnect the battery and observe safety precautions.
Basic Step #5
Inspect the wiring harness of the reductant level sensor for any damage or chafed wires. Such damage can cause erratic values to be sent to the ECM, potentially leading to the unnecessary replacement of the sensor. Repair any bare wires or corrosion before proceeding. Ensure that the harness is securely fastened and kept away from any moving parts.
This article is intended solely for informational purposes, and the technical data and service bulletins specific to your vehicle should always take precedence.
