Exhaust Gas Recirculation B Position Control Learning Limit Exceeded
What does that mean?
This is a generic diagnostic trouble code (DTC) for the powertrain that generally applies to OBD-II vehicles equipped with an Exhaust Gas Recirculation (EGR) system. This may include, but is not limited to, vehicles from Dodge/Ram (Cummins), Chevy/GMC (Duramax), Honda, Jeep, Hyundai, etc.
Although generic, the exact repair steps may vary depending on the year, make, model, and powertrain configuration.
If your OBD-II equipped vehicle has stored a P049E code, it means the Powertrain Control Module (PCM) has detected a malfunction in a specific position control of the lowered Exhaust Gas Recirculation (EGR) valve. B refers to a specific position of the lowered EGR valve.
The lowered EGR valve system is designed to recirculate a portion of the spent exhaust gases back into the intake manifold, in measured increments, so it can be burned a second time. This process is essential in reducing nitrogen oxide (NOx) particles that are released into the atmosphere as a byproduct of internal combustion and diesel engine operation. NOx is suspected to be a contributing factor to the depletion of the ozone layer from exhaust emissions. NOx emissions are regulated by federal mandate in North American vehicles.
The learning limit is a programmed degree that reflects the minimum and maximum parameters to which a specific position (B) of the lowered EGR valve can adapt. If the PCM detects that the actual position of the EGR valve is beyond these parameters, a P049E code will be stored and a Malfunction Indicator Lamp (MIL) may illuminate. In some vehicle applications, multiple ignition cycles (with a fault) are required for the MIL to light up.
How severe is this DTC?
Since the P049E code relates to the EGR system, it should not be considered severe.
What are some of the symptoms of the code?
Symptoms of a P049E fault code may include:
There will likely be no symptoms associated with this code
Slightly decreased fuel efficiency
Possible driving issues
What are some common causes of the code?
Causes
of this P049E code may include:
Faulty EGR valve
Faulty EGR sensor
Incorrect PCM or PCM programming error
What are the troubleshooting steps for P049E?
I would typically start my diagnosis by locating the vehicle’s diagnostic connector and retrieving all stored codes and associated data. I would write down all this information in case I need it as I proceed with my diagnosis. Then, I would test the vehicle to see if the code resets immediately.
By searching the vehicle’s Technical Service Bulletins (TSBs) for entries matching the vehicle, stored codes, and displayed symptoms, you might discover the solution to your (potentially difficult) diagnosis. Since TSB entries come from thousands of repair specialists, they often contain very helpful details.
If the P049E is stored after clearing the codes, I would have access to a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable source of vehicle information.
Now, I would perform a visual inspection of the EGR valve and all associated wiring and connectors. Focus on wiring harnesses routed near hot exhaust components and the sharp edges often associated with exhaust shields.
NOTE: Disconnect all associated controllers from the circuit before testing resistance/continuity with the DVOM.
Using wiring diagrams and connector pinout charts, located in your vehicle information source, test each EGR valve connector circuit (with the DVOM) for the appropriate signal. It may be necessary to manually activate the EGR system using the scanner, as most systems require a defined speed before automatic activation can occur. Circuits that do not meet manufacturer specifications will need to be traced back to the source (usually the PCM connector) and retested. If the PCM output signal is not detected, suspect a PCM programming error or faulty PCM. Otherwise, repair or replace open/short-circuited circuits as needed.
Use the DVOM to test the actual EGR valve and integrated sensors if all circuits meet manufacturer specifications. Your vehicle information source will again provide information for testing this component. If the lowered EGR valve and all (integrated) sensors do not align with manufacturer specifications, suspect it is faulty.
This code should only appear in vehicles equipped with a lowered EGR valve.