P0176Fuel Composition Sensor Circuit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- The fuel composition sensor is fitted only to flex-fuel vehicles that can run on petrol or ethanol up to E85. GM uses a capacitive sensor in the fuel line whose square-wave output frequency gives the ethanol content – 50 Hz for E0 up to 150 Hz for E100 – while the pulse width carries the fuel temperature. Ford has calculated the ethanol content from the oxygen sensor feedback after refuelling since model year 2000 and has no such sensor. P0176 is the general circuit fault of this sensor without telling low from high. GM's current documents use P0178/P0179 instead, so P0176 is mainly to be expected on older flex-fuel vehicles or other makes. GM issued a special coverage for 2013–2014 flex-fuel models (10 years/150,000 miles) because road salt could make the sensor fail electrically, turning on the MIL and disabling remote start. No manufacturer document using exactly this code was found; the description rests on CARB's circuit monitoring requirement and component information.
- What you may notice
- Check engine light on
- Ethanol content in scan data implausible or frozen
- Starting problems on E85
- Likely causes
- LikelyFlex-fuel sensor electrically failed (corrosion from road salt)
- LikelyConnector or wire corroded, open or shorted
- PossibleSupply (relay, fuse) missing
- RareEngine control module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · Often possible to do yourself.Typical cost: €80 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.