Technical Description of OBD-II Trouble Code
The circuit for the reductant temperature sensor is experiencing a range/performance issue.
What does that mean?
This diagnostic trouble code (DTC) is a generic powertrain code that applies to many OBD-II vehicles (1996-newer), including vehicles from Mercedes, Sprinter, Ford, GMC, Chevrolet, etc. The exact repair steps may vary depending on the year, make, model, and powertrain configuration.
A stored code P2043 indicates that the powertrain control module (PCM) has detected an abnormal voltage level in the reductant temperature sensor circuit. This code is specific to vehicles with a clean burning diesel engine.
The catalyst system is responsible for reducing exhaust emissions, and some applications also have a NOx trap.
Exhaust gas recirculation (EGR) systems further reduce NOx emissions. However, larger and more powerful diesel engines cannot meet strict U.S. emission standards with just the EGR, diesel particulate filter/catalytic converter, and NOx trap. This led to the development of selective catalytic reduction (SCR) systems.
SCR systems inject a reductant compound or diesel exhaust fluid (DEF) into the exhaust system to improve filtration efficiency and reduce harmful emissions. The PCM or a stand-alone controller monitors and controls the entire SCR system, including the timing of DEF injection. Precise DEF injection is crucial for maintaining acceptable exhaust temperature and optimizing pollutant filtration.
The reductant/regeneration supply pump pressurizes the DEF in the liquid reductant system when needed. The PCM monitors the supply pump voltage and pressure sensors to detect any leaks in the system.
If the PCM detects an abnormal voltage level in the reductant temperature sensor circuit, it will store a code P2043 and may illuminate the malfunction indicator lamp (MIL). Multiple ignition cycles with a failure may be required for MIL illumination.
Example of a DEF reductant tank:
What is the severity of this DTC?
A stored code P2043 should be considered severe and addressed as quickly as possible. It could disable the SCR system and potentially cause catalyst damage if the underlying conditions are not resolved promptly.
What are some of the symptoms of the code?
Symptoms of a P2043 trouble code may include:
What are some of the common causes of the code?
Possible causes for this code include:
What are some P2043 troubleshooting steps?
To diagnose a code P2043, you will need a diagnostic scanner, a digital volt/ohmmeter (DVOM), and vehicle-specific diagnostic information.
Refer to your vehicle information source to find a technical service bulletin (TSB) that matches your vehicle’s details and symptoms. This TSB may provide helpful diagnostic information.
Use the scanner to retrieve all stored codes and freeze frame data. Write down this information before clearing the codes and test-drive the vehicle until the PCM enters readiness mode or the code is reset.
If the PCM enters readiness mode, the code is intermittent and may be more challenging to diagnose. In this case, the underlying conditions may need to worsen before an accurate diagnosis can be made.
If the code is immediately reset, consult your vehicle information source for diagnostic flowcharts, connector pin-out charts, connector face views, and component testing procedures/specifications.
Step 1
Use the DVOM to test the reductant temperature sensor according to the manufacturer’s specifications. Consider components that do not test within the allowable parameters as defective.
Step 2
If the actual reductant temperature is within specifications, the code P2043 persists, and the sensor is functioning correctly, use the DVOM to test the input and output signal circuits between the temperature sensor and the PCM/SCR controller. Disconnect all controllers before conducting the DVOM tests.
