P2457 on the 6.7L Power Stroke is an exhaust gas recirculation (EGR) cooling system performance fault. The EGR cooler uses engine coolant to lower the temperature of exhaust gas before it re-enters the intake, which is required for emissions and to protect intake components. P2457 sets when the PCM determines the EGR cooler is not lowering the exhaust gas temperature enough, meaning it is not performing to specification.
The EGR cooler on the 6.7L works in an extremely hot, sooty, high-pressure environment, which makes clogging and reduced heat transfer common over the miles. P2457 tells you the cooler is no longer doing its job, whether from internal plugging, low coolant flow, or a sensor issue. Because a failing EGR cooler can eventually crack and leak coolant, addressing P2457 early can prevent a larger and more expensive repair.
What P2457 means
The PCM monitors exhaust gas temperature through the EGR cooler and expects a certain drop across it. P2457 sets when that temperature drop is smaller than expected, indicating the cooler is not transferring heat effectively. This points to internal soot plugging, restricted coolant flow, low coolant, or a temperature sensor fault rather than a simple electrical circuit problem.
Common causes
- Soot-plugged or scaled EGR cooler with reduced heat transfer
- Low coolant level or air in the cooling system
- Restricted coolant flow through the cooler
- Faulty exhaust gas temperature sensor or wiring
- A partially failed or bypassing EGR cooler
Symptoms
- Check engine light with P2457 stored
- Reduced power or a derate in some cases
- Higher intake or exhaust temperatures
- Coolant loss if the cooler has started to crack
- Companion EGR or exhaust temperature codes
How to diagnose it
Confirm the coolant level is correct and the cooling system is free of air, since low coolant or air reduces cooler performance. With a scan tool, view the relevant exhaust gas temperature data and evaluate the temperature drop across the cooler. Check the EGR-related temperature sensors and wiring for faults that would mimic poor performance. Inspect for coolant loss or exhaust in the coolant, which indicates a cracking cooler. Evaluate whether the cooler is internally plugged with soot.
How to fix it
Correct low coolant and bleed air from the system first, then repair any temperature sensor or wiring fault, as these can resolve the code without major work. If the cooler is internally plugged, scaled, or cracked so it no longer transfers heat properly, replace the EGR cooler. Confirm coolant flow through the cooler is unrestricted. After the repair, clear the code, verify the temperature drop across the cooler is back in range, and road test. For EGR coolers, gaskets, and related parts for your 6.7L Power Stroke, contact sales@coredieselparts.com.
Frequently asked questions
Can low coolant cause P2457?
Yes. Low coolant or trapped air reduces heat transfer through the EGR cooler, so the exhaust gas is not cooled enough. Check and correct the coolant level before replacing the cooler.
Is P2457 a sign the EGR cooler is failing?
Often, yes. A plugged or scaled cooler cannot transfer heat effectively, and a cooler in that condition can eventually crack and leak coolant. Addressing it early can prevent a bigger repair.
Will P2457 cause coolant loss?
Not by itself, but a cooler that has degraded to the point of cracking will leak coolant into the exhaust. Watch for coolant loss and white exhaust smoke as warning signs.
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