OBD-II code · Powertrain (generic, extended)
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.
Is it safe to drive with P2478?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelySensor element aged
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.6–1.8 h
- Emissions test
- Likely to fail
- Parts involved
- Egt Sensor B1s1
Related codes
- P2479Exhaust Gas Temperature Out of Range Bank 1 Sensor 2
- P247AExhaust Gas Temperature Out of Range Bank 1 Sensor 3
- P247BExhaust Gas Temperature Out of Range Bank 1 Sensor 4
- P247CExhaust Gas Temperature Out of Range Bank 2 Sensor 1
- P247DExhaust Gas Temperature Out of Range Bank 2 Sensor 2
- P247EExhaust Gas Temperature Out of Range Bank 2 Sensor 3
- P247FExhaust Gas Temperature Out of Range Bank 2 Sensor 4
- P2475Exhaust Gas Temperature Sensor Circuit Low Bank 2 Sensor 4
- P2476Exhaust Gas Temperature Sensor Circuit High Bank 2 Sensor 4
- P2477Exhaust Gas Temperature Sensor Circuit Intermittent or Erratic Bank 2 Sensor 4
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.