P2457 code meaning
EGR Cooler A Efficiency Below Threshold
Powertrain system Generic code P24xx codes Check engine light
What P2457 means
The EGR cooler is supposed to bring recirculated exhaust close to coolant temperature; P2457 says cooler A no longer removes enough heat, as CARB requires diesel systems to detect. GM rates efficiency as the drop across the cooler divided by the gap between inlet gas and coolant; in the 2017 tables the Duramax fails below 60 %, the MDE engine family below 50 %, each after two trips. Ford's 6.7 L diesel instead watches the outlet gas: above coolant plus 70 °C in 2013 and plus 88 °C in 2023 for 12 s, with the bypass in cooling position; gasoline engines with cooled EGR use a flow ratio. Ford traced P2457 on 2018 to 2019 F-150 3.0 L diesels to loose screws in the bypass module, and Hino fixed 2012 trucks by software. Soot fouling and a bypass flap stuck in bypass are common; cooler B is P241F.
P2457 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyHard
- Typical labor0.5 to 8 hours
- Clears after repairAfter a drive cycle
Symptoms of P2457
- Malfunction indicator lamp on
- Higher NOx, sometimes reduced EGR or power
- Coolant loss or white smoke if the cooler is also leaking
Common causes of P2457
- Most likelyCooler passages fouled with soot and lacquer
- PossibleBypass flap stuck in bypass position or bypass module loose
- PossibleEGR outlet temperature sensor reading too high
- Less likelyLow coolant level or poor coolant flow through the cooler
- Less likelyMonitor software misjudging efficiency (known on some trucks)
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
EGR coolerEGR temperature sensor
What each part of P2457 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 4 | Area: auxiliary emission controls (catalytic converter, EGR, EVAP). |
| 57 | The exact fault in that area. |
What to do next
- Note P2457 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P2457
What does P2457 mean?
P2457 means "EGR Cooler A Efficiency Below Threshold". The EGR cooler is supposed to bring recirculated exhaust close to coolant temperature; P2457 says cooler A no longer removes enough heat, as CARB requires diesel systems to detect. It is a generic code, so it means the same on every make.
Is it safe to drive with P2457?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P2457 fail an emissions test?
Yes, it can. P2457 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P2457 to fix?
Difficulty: hard. A typical repair takes 0.5 to 8 hours of work. This is a job for a workshop.
Will P2457 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.