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

P2478

Exhaust Gas Temperature Out of Range Bank 1 Sensor 1

The EGT sensor at bank 1 sensor 1 reports a value outside its plausible operating range over time - typically a degraded element giving an offset that the substitute logic flags as implausible.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number4 / 78

Possible causes

  • Sensor element aged high

Inspection / repair

  • Difficulty: medium
  • DIY: possible
  • Estimated cost: 120–400 €
  • Estimated time: 0.6–1.8 h
  • Component: egt sensor b1s1
  • MIL / check engine light
  • emissions-relevant

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