Error Code P049D is defined as EGR A Control Position Exceeded Learning Limit. This trouble code is a generic code, which means it applies to all vehicles equipped with OBD-II system and made in 1996 up to present, particularly those with EGR (exhaust gas recirculation system). This includes but not limited to vehicles from Dodge or Ram (Cummins), Chevrolet or GMC (Duramax), Honda, Jeep, Hyundai, and other makes. Specifications on the definition, troubleshooting, and repairs, of course, vary from one make and model to another.
Error Code P049D means the PCM (powertrain control module, also known as ECM or engine control module in other vehicle makes) has detected a malfunction in a certain control position of the step-down exhaust gas recirculation (EGR) valve. B refers to a specific position of the EGR step-down valve.
The step-down EGR valve system works by delivering a part of spent exhaust gases back to the intake manifold, in measured increments, so that it can be burned a second time. This reduces the nitrous oxide (NOx) particles that are released into the atmosphere as a side effect of internal combustion and diesel engine operation, making it a critical process.
This process is critical in the reduction of nitrous oxide (NOx) particles that are released into the atmosphere as a side effect of internal combustion and diesel engine operation. NOx is suspected of being a contributing factor in ozone depletion from exhaust emissions. NOx emissions are regulated by federal mandate in North American vehicles.
If the PCM determines that the actual position of the EGR valve is beyond these specifications set by the manufacturer, a code P049D will be stored, and a malfunction indicator lamp (MIL) may be illuminated. In some vehicle applications, multiple ignition cycles (with a failure) are required for MIL illumination.
This code should be exhibited only in vehicles equipped with a step-down EGR valve.
As with other error codes, this code activates the Check Engine light and registers the code to the vehicle’s memory system. In most cases, there will be no other noticeable symptoms. In some cases, however, noticeable symptoms would be:
- Diminished engine power and performance
- Poor acceleration
- Increase in fuel consumption
Common causes for this code include:
- Defective EGR valve
- Defective EGR sensor
- Faulty PCM or programming error (rare)
How to Check
Diagnostics for this code starts by retrieving all stored codes and related data in the vehicle’s computer. Take note of the code, and then reset the codes before taking the vehicle for a test drive to see if the code comes back.
Use the TSB (technical service bulletins) and look for the entry; match the vehicle, codes stored, and symptoms exhibited. Most manufacturers post updated solutions for errors like this.
If this error code reappears after clearing the code, then use you will need a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable vehicle information source.
Next, perform a thorough visual inspection of the EGR valve and all related connectors and wirings. Focus on the wiring harness routed near hot exhaust components; jagged edges are often associated with exhaust shields.
Make sure you disconnect all related controllers from the circuit before testing resistance or continuity using the DVOM.
Using wiring diagrams and connector pin out charts, find the vehicle information source. Then, use the DVOM to test each EGR valve connector circuit for the right signal. You may have to activate the EGR system manually using the scanner as most systems require a set rate of speed before automatic activation can occur. Circuits that don’t conform to specifications set by the manufacturer will need to be followed back to the source (usually the PCM connector) and retested. If the output signal from the PCM is not detected, suspect a defective PCM or PCM programming error. Instead of that, repair or replace open/shorted circuits as required.
Test the actual EGR valve and integrated sensors using the DVOM. Find out if all circuits comply with the manufacturer’s specifications. Check your vehicle information source to test this part.
If the step-down EGR valve and all (integrated) sensors are outside the specifications set by the manufacturer, then you may have a defective valve, which needs a replacement.
How to Fix
Common repairs for this code include:
- EGR Valve Replacement
- Repair or replace open/shorted circuits as required
Since this code refers to a problem in the EGR, it is not considered as severe.