🔥 Severity of DTC P2039
A stored code P2039 should be considered serious and addressed as quickly as possible.
- Impact on the SCR system: The selective catalytic reduction (SCR) system may be disabled.
- Risk to the catalyst: Damage to the catalyst may occur if the conditions that led to the code being stored are not corrected promptly.
🚨 Symptoms of Code P2039
Symptoms of a P2039 fault code may include:
- Reduced energy efficiency
- Excessive black smoke from the exhaust
- Decreased engine performance
- Presence of other codes related to the SCR system
⚙️ Common Causes of Code P2039
Possible causes include:
- Faulty reductant air pressure sensor (A)
- Open or shorted circuits in the reductant injection air pressure sensor system
- Faulty SCR controller / PCM or programming error
🛠️ Troubleshooting Steps for Code P2039
-
Check the integrity of the reductant/regeneration system
- Ensure the system is not losing pressure, either internally or externally.
- Activate the pump to generate pressure and inspect the system for any leaks.
-
Pressure check
- Use a fuel pressure tester to manually monitor the pressure in the reductant system.
- Check the supply pump and injector for any leaks.
- Corrective action: Repair any leaks (internal or external) before continuing diagnosis.
-
Retrieving diagnostic data
- Connect a diagnostic scanner to the OBD-II port to retrieve all stored codes and freeze frame data.
- Note this information before clearing the codes and testing the vehicle to see if the PCM enters readiness mode or if the code resets.
-
Interpreting intermittent codes
- If the PCM enters readiness mode, it indicates that the code is intermittent and may be difficult to diagnose.
- In this case, the conditions that led to the code being stored may need to worsen before an accurate diagnosis can be made.
-
Consulting technical information
- Refer to technical service bulletins (TSBs) specific to your vehicle’s year, make, and model, including engine size, stored codes, and symptoms presented.
- Also consult wiring diagrams, pinout diagrams, and component testing procedures.
-
Testing sensors and circuits
- Step 1: Use a digital volt/ohmmeter (DVOM) to test the reductant injection system pressure sensors according to the manufacturer’s specifications.
- Components that do not fall within the maximum allowable parameters should be considered faulty.
- Step 2:
- If the reductant injection pressure is correct, but the P2039 code persists, test the input and output signal circuits between the sensors and the PCM/SCR controller.
- Tip: Disconnect all controllers before performing these tests.
- Step 1: Use a digital volt/ohmmeter (DVOM) to test the reductant injection system pressure sensors according to the manufacturer’s specifications.
Note: Codes related to reductant injector sensors are often caused by supply pumps leaking internally.
Conclusion
The P2039 code indicates a critical problem in the SCR system control circuit, which can affect battery load and the vehicle’s overall performance.
To diagnose and correct this issue, it is essential to use appropriate diagnostic tools, consult vehicle-specific technical documentation, and thoroughly inspect the system to identify any anomalies.
If in doubt, it is recommended to seek professional assistance to ensure a safe and accurate repair.