P2478–P247F Exhaust Gas Temperature Out of Range Bank 1 Sensor 1
The value has run past the end of the range the ECU can work with, so it has stopped trying to compensate and logged the fault instead.
Can you drive it? The engine light will stay on and the car may run in a reduced-power mode. Read the freeze-frame data to see the conditions the fault was logged under.
Which code is which
Same fault, different cylinder or bank — diagnosed the same way. Several set together usually means one shared cause.
| Code | Definition | Severity |
|---|---|---|
P2478 | Exhaust Gas Temperature Out of Range Bank 1 Sensor 1 | Investigate soon |
P2479 | Exhaust Gas Temperature Out of Range Bank 1 Sensor 2 | Investigate soon |
P247A | Exhaust Gas Temperature Out of Range Bank 1 Sensor 3 | Investigate soon |
P247B | Exhaust Gas Temperature Out of Range Bank 1 Sensor 4 | Investigate soon |
P247C | Exhaust Gas Temperature Out of Range Bank 2 Sensor 1 | Investigate soon |
P247D | Exhaust Gas Temperature Out of Range Bank 2 Sensor 2 | Investigate soon |
P247E | Exhaust Gas Temperature Out of Range Bank 2 Sensor 3 | Investigate soon |
P247F | Exhaust Gas Temperature Out of Range Bank 2 Sensor 4 | Investigate soon |
The definition
P2478: Exhaust Gas Temperature Out of Range Bank 1 Sensor 1.
P2478 is a manufacturer-specific powertrain code (the engine or gearbox). Its meaning is set by the carmaker rather than by the SAE standard, so a generic OBD-II reader will often show it as an unknown code or misread it.
What to check first
Cheapest and fastest checks first:
- Read the freeze-frame data stored with the fault - engine speed, load and temperature at the moment it logged tell you whether this happens cold, hot or under load.
- Check the connector at the part for corrosion, and that it is fully seated.
- Clear the code and see whether it returns, and under what conditions.
Reading the code is the easy part
A code names the circuit that complained. What tells you why is watching the sensor behind it while the engine runs — and that is where a code reader stops and a diagnostic tool starts.
VAGPULSE reads every module in a VW, Audi, Skoda or SEAT — not just the engine — shows the live measuring blocks behind this fault, gives you the freeze-frame conditions it was logged under, and clears it once you have fixed it. It also does what a generic OBD reader cannot on a VAG: service resets, coding, adaptations, and Stage 1–3 flashing with your original file saved first.
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Common questions
What does P2478 mean?
P2478 means Exhaust Gas Temperature Out of Range Bank 1 Sensor 1. The value has run past the end of the range the ECU can work with, so it has stopped trying to compensate and logged the fault instead.
Can I drive with P2478?
The engine light will stay on and the car may run in a reduced-power mode. Read the freeze-frame data to see the conditions the fault was logged under.