P2457 — EGR Cooler A Efficiency Below Threshold

P2457: EGR Cooler A Efficiency Below Threshold — what it means, the affected system and what to check before replacing parts.

Meaning, symptoms, causes and checks

EGR Cooler A Efficiency Below Threshold. Basic catalogue definition; diagnostic details have not yet been reviewed.

Affected system: Powertrain

Symptoms

  • A check-engine warning may appear.
  • Acceleration may weaken or engine power may be restricted.

Possible causes

  • Soot deposits may obstruct the EGR cooler.
  • Insufficient coolant, leaks or restricted coolant flow may reduce EGR cooling.
  • Inaccurate EGR temperature-sensor readings are another possible cause; charge-air cooler restriction is mentioned less often.

What to check

  • With the engine cooled, check coolant level and look for leaks near EGR cooling hoses.
  • Inspect the EGR cooler for soot or flow restriction by a procedure suitable for the vehicle.
  • Review EGR temperature-sensor data; examine the charge-air cooler only if prior checks are inconclusive.

Also written as: P2457-00, P245700 (some scan tools add the fault-type byte, e.g. -00).