OBD-II reference

All 9.533 generic OBD-II codes, explained in detail.

Causes, inspection steps and sources — a comprehensive DIY archive. Created and maintained with love for the detail. Good luck and have fun!

Powertrain generic / SAE

P2457

EGR Cooler Performance

The EGR cooler does not lower exhaust gas temperature as expected — typically internal coolant fouling, a partial blockage, or a cracked cooler that mixes coolant with exhaust gas.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number4 / 57

Possible causes

  • Cooler internally clogged with soot high
  • Cooler cracked, coolant entering exhaust medium

Symptoms

  • Check engine light on
  • Pinging or knocking under load
  • Power loss and hesitation
  • Possible rough idle
  • Failed emissions inspection (NOx)

Inspection / repair

  • Difficulty: hard
  • DIY: shop recommended
  • Estimated cost: 400–2500 €
  • Estimated time: 2–8 h
  • Component: egr cooler
  • Component: egr temperature sensor
  • MIL / check engine light
  • emissions-relevant
  • drive cycle required

Sources

References

How to read OBD-II codes

The first letter names the vehicle system, the second digit distinguishes generic from manufacturer-specific, the remaining digits group fault area and number.

PPowertrain: engine, transmission, emissions
BBody: chassis trim, comfort, interior
CChassis: suspension, brakes, steering
UNetwork: CAN, control modules, communication