Code P2457 indicates that the powertrain control module (PCM) has detected the exhaust gas recirculation (EGR) cooler is not reducing exhaust gas temperatures as expected. The EGR cooler is a heat exchanger that lowers exhaust gas temperature before it enters the intake manifold; this code sets when the temperature drop across the cooler is below a calibrated threshold.
Soot and carbon deposits accumulate inside the cooler passages over time, reducing heat transfer and causing low efficiency. This is the most common cause.
A sensor that reads incorrectly (either before or after the cooler) can falsely indicate insufficient cooling, even if the cooler is functioning properly.
An EGR valve stuck open or closed, or one that does not respond correctly to commands, can disrupt exhaust flow through the cooler and affect temperature readings.
Low coolant level, air pockets, or a clogged coolant passage can prevent the cooler from transferring heat effectively, leading to a false efficiency fault.
Damaged, corroded, or loose wiring/connectors at the EGR temperature sensors or EGR valve can cause erratic signals that mimic a cooler efficiency problem.
A faulty PCM is a rare possibility and should only be considered after all other causes have been thoroughly ruled out.
It means the engine computer has determined that the EGR cooler is not reducing exhaust gas temperatures as much as expected, likely due to a clogged cooler, faulty sensor, or EGR valve issue.
Driving for a short period is usually safe, but the problem should be addressed promptly. Ignoring it may lead to increased emissions, engine knocking, and potential damage to other components over time.
No, PCM failure is extremely rare for this code. Many drivers are incorrectly told to replace the PCM, but the root cause is almost always a mechanical issue with the EGR cooler, a sensor, or the EGR valve. Replacing the PCM without proper diagnosis will not fix the problem.
A clogged cooler often shows a smaller-than-expected temperature drop between the inlet and outlet sensors when the EGR valve is commanded open. Physical inspection or a backpressure test can confirm excessive soot buildup.