The Elm Obd2 20720 diagnostic trouble code (DTC) is a common issue encountered by Mercedes-Benz owners, particularly those with ML-Class W164 (2005-2012) and GL-Class X164 (2006-2012) models. This code indicates a problem with the intake manifold runner position sensor/switch circuit bank 2. Understanding this code and its potential causes can help you diagnose and fix the issue effectively.
Decoding the ELM OBD2 20720 Code
The ELM OBD2 20720 code breaks down as follows:
- 20720: The specific code indicating the fault.
- Intake Manifold Runner Position Sensor/Switch Circuit: This points to a problem within the electrical circuit that controls the intake manifold runner position.
- Bank 2: This refers to the side of the engine that does not contain cylinder number one. This is important for pinpointing the location of the faulty component.
Potential Causes of the ELM OBD2 20720 Code
Several factors can trigger the ELM OBD2 20720 code:
- Faulty Intake Manifold Runner Position Sensor: The sensor itself might be malfunctioning, sending incorrect signals to the engine control unit (ECU).
- Wiring Issues: Damaged, corroded, or loose wiring within the sensor circuit can disrupt the signal transmission.
- Carbon Buildup: Excessive carbon buildup on the intake manifold runners or the sensor can hinder its movement and accuracy.
- Vacuum Leaks: Leaks in the intake manifold vacuum system can affect the runner position and trigger the code.
- Faulty ECU: In rare cases, a malfunctioning ECU can misinterpret signals and generate the ELM OBD2 20720 code.
Diagnosing the ELM OBD2 20720 Code with an ELM327 Device
Using an ELM327 OBD2 scanner can help pinpoint the cause:
- Read the Code: Connect the ELM327 device to your vehicle’s OBD2 port and read the stored codes. Confirm the presence of the 20720 code.
- Inspect Wiring: Visually inspect the wiring harness connected to the intake manifold runner position sensor for any visible damage or loose connections.
- Check Sensor Voltage: Use a multimeter to check the voltage signal from the sensor. Compare the readings with the manufacturer’s specifications.
- Test Vacuum System: Inspect the intake manifold for vacuum leaks using a smoke machine or a vacuum gauge.
- Monitor Live Data: Use the ELM327 device to monitor the live data from the sensor while operating the engine. Observe any unusual fluctuations or inconsistencies.
Resolving the ELM OBD2 20720 Code
Based on your diagnosis, the solution could involve:
- Sensor Replacement: If the sensor is faulty, replacing it is usually the solution.
- Wiring Repair: Repair or replace any damaged or corroded wiring within the sensor circuit.
- Carbon Cleaning: Clean the intake manifold runners and the sensor to remove carbon buildup.
- Vacuum Leak Repair: Seal any detected vacuum leaks in the intake manifold.
- ECU Reprogramming or Replacement: In rare cases, the ECU might require reprogramming or replacement.
Conclusion: Addressing the ELM OBD2 20720 Code
The ELM OBD2 20720 code signifies a problem within the intake manifold runner position sensor/switch circuit on Bank 2 of your Mercedes-Benz. By systematically diagnosing the issue with an ELM327 device and following the troubleshooting steps outlined above, you can effectively address the underlying cause and restore optimal engine performance. Remember to consult your vehicle’s repair manual for specific instructions and safety precautions.
