Symptoms
and Severity
Since P2457 is related to the exhaust emission system, it is not considered an urgent code. The symptoms of a P2457 code may include:
- There may be no symptoms when this code is stored
- Reduced fuel efficiency
- A stored code
- Malfunction indicator lamp illumination
- Coolant leak
- Exhaust leak
- Exhaust temperature sensor codes
Causes
Causes
potential causes for setting this code are as follows:
- Low coolant
- Faulty EGR temperature sensor
- Faulty exhaust temperature sensor
- Exhaust leaks
- Clogged EGR cooler
- Engine overheating
Diagnostic and Repair Procedures
A good starting point is always to check the technical service bulletins (TSBs) for your specific vehicle. Your issue may be a known problem with a known fix released by the manufacturer and can save you time and money when diagnosing.
A diagnostic scanner, a digital volt/ohmmeter, a vehicle service manual (or equivalent), and an infrared thermometer with a laser pointer are all tools I would use to diagnose a P2457.
I might start with a visual inspection of the wiring harnesses and connectors associated with the EGR temperature sensor and the exhaust temperature sensor. Carefully examine harnesses that are near hot exhaust pipes and manifolds. Test the battery load, check the battery terminal ends, battery cables, and alternator output before proceeding.
I like to connect the scanner to the vehicle and retrieve all stored codes and freeze frame data at this point. Record the information as you may need it if this turns out to be an intermittent code.
I would observe the scanner data stream to determine if there was actually EGR cooling. Narrow the data stream to include only relevant information for a faster and more accurate data response. If the scanner indicates that the actual temperature inputs are within specifications, suspect a faulty PCM or PCM programming error.
If the EGR temperature sensor data is erratic or does not match the desired parameters, test the sensor following the manufacturer’s recommendations. Replace the sensor if it does not meet the manufacturer’s specifications. If the sensor proves to be in good condition, start testing the EGR temperature sensor circuits. Disconnect all associated controllers before testing with the DVOM. Repair or replace open or shorted circuits as needed.
If the EGR temperature sensor electrical system appears to be functioning normally, use the infrared thermometer to check the exhaust gas temperature at the EGR cooler inlet and at the EGR cooler outlet (with the engine running and at normal operating temperature). Compare your results with the manufacturer’s specifications and replace faulty components if necessary.
Additional Diagnostic Notes:
- Aftermarket mufflers and other exhaust components can cause exhaust temperature variations that could lead to this code being stored
- Exhaust backpressure issues, created by an inadequate diesel particulate filter (DPF), are known to contribute to P2457 storage conditions
- Diagnose and repair DPF-related codes before attempting to diagnose this code
- If the EGR system has been modified using an EGR blocking kit (currently offered by OEMs and aftermarket companies), this type of code may be stored