Technical Description of OBD-II Trouble Code
The learning limit for the control position of the Exhaust Gas Recirculation B has been exceeded
What does that mean?
This is a generic powertrain diagnostic trouble code (DTC) that typically applies to OBD-II vehicles equipped with an exhaust gas recirculation (EGR) system. This may include vehicles from various manufacturers such as Dodge / Ram (Cummins), Chevy / GMC (Duramax), Honda, Jeep, Hyundai, etc.
Although it is a generic code, the specific repair steps may vary depending on the year, make, model, and powertrain configuration of the vehicle.
If your OBD-II equipped vehicle has stored a code P049E, it indicates that the powertrain control module (PCM) has detected a malfunction in a specific control position of the step-down exhaust gas recirculation (EGR) valve. The “B” refers to a particular position of the EGR step-down valve.
The step-down EGR valve system is designed to recycle a portion of the exhaust gases back into the intake manifold in measured increments, allowing them to be burned a second time. This process is crucial for reducing the release of nitrous oxide (NOx) particles into the atmosphere, which are a byproduct of internal combustion and diesel engine operation. NOx emissions are regulated by federal mandate in North American vehicles due to their contribution to ozone depletion.
The learning limit is a programmed range that represents the minimum and maximum parameters to which a specific position (B) of the step-down EGR valve can adapt. If the PCM detects that the actual position of the EGR valve is outside of these parameters, it will store a code P049E and may illuminate a malfunction indicator lamp (MIL). In some cases, multiple ignition cycles with a failure are required for the MIL to illuminate.
What is the severity of this DTC?
Since the code P049E relates to the EGR system, it should not be considered severe.
What are some of the symptoms of the code?
Symptoms associated with a P049E trouble code may include:
What are some of the common causes of the code?
Possible causes for this P049E EGR code may include:
What are some P049E troubleshooting steps?
To diagnose this issue, start by locating the vehicle diagnostic connector and retrieving all stored codes and related data. Write down this information for reference during the diagnosis process. Next, test drive the vehicle to see if the code is immediately reset.
Search for vehicle technical service bulletins (TSB) that match the vehicle, stored codes, and exhibited symptoms. These TSB entries, compiled from repair specialists, often provide valuable details that can assist in the diagnosis.
If the P049E code is stored after clearing the codes, use a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable vehicle information source for further testing.
Begin by visually inspecting the EGR valve, as well as all related wiring and connectors. Pay attention to wiring harnesses near hot exhaust components and any sharp edges associated with exhaust shields.
NOTE: Before testing resistance/continuity with the DVOM, disconnect all related controllers from the circuit.
Using wiring diagrams and connector pinout charts from your vehicle information source, test each individual EGR valve connector circuit with the DVOM to check for the appropriate signal. In some cases, manual activation of the EGR system using the scanner may be necessary, as most systems require a specific rate of speed for automatic activation. If any circuits do not meet the manufacturer’s specifications, trace them back to the source (usually the PCM connector) and retest. If no output signal from the PCM is detected, suspect a defective PCM or PCM programming error. Otherwise, repair or replace any open/shorted circuits as needed.
If all circuits are in compliance with the manufacturer’s specifications, use the DVOM to test the actual EGR valve and integrated sensors. Your vehicle information source will provide instructions for testing this component. If the step-down EGR valve and all integrated sensors do not align with the manufacturer’s specifications, it is likely that the valve is defective.
This code should only appear in vehicles equipped with a step-down EGR valve.
