P0179
Fuel Composition Sensor Circuit High Input
The flex-fuel composition sensor signal exceeds the maximum threshold. Likely shorted to voltage, open ground or failed sensor.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Signal wire shorted to voltageCommon
- Sensor failedPossible
- Connector pins corroded - high contact resistanceLess likely
Parts involved
- Flex Fuel Composition Sensor
- Sensor Wiring
P0179 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.