P0179: Fuel Composition Sensor Circuit High Input
Can you still drive? Yes, but the engine may run richer than normal, which can reduce fuel economy and increase emissions.
What Does P0179 Mean?
Code P0179 means the fuel composition sensor is sending a voltage signal higher than the maximum expected range to the ECM. This usually indicates an open circuit, a short to voltage in the sensor wiring, or a failed sensor. The ECM cannot properly adjust fuel delivery for varying ethanol blends when this code is present.
Need to read your codes?
An OBD-II scanner lets you read and clear diagnostic trouble codes from your vehicle's computer. Most scanners work with any car made after 1996.
Browse OBD-II Scanners on AmazonCommon Causes
- Open circuit in the sensor wiring
- Short to battery voltage in the harness
- Failed fuel composition sensor
- Faulty ECM connector
Symptoms
- Check engine light on
- Engine runs rich
- Poor fuel economy
- Rough idle or hesitation
Diagnostic Steps
- 1Read freeze frame data and check sensor voltage reading
- 2Verify reference voltage at the sensor connector
- 3Check for open circuits or shorts to voltage in the wiring
- 4Test sensor signal output with a multimeter
- 5Replace the sensor if wiring checks pass
Recommended Parts & Tools
fuel composition sensor
automotive multimeter
Estimated Repair Cost
| Type | Estimated Cost |
|---|---|
| Total Repair Cost Range | $120 - $450 |
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Chat with AI About P0179Commonly Affected Vehicles
Related Recalls
1 Active Recall — 2026 Chevrolet Tahoe
The following NHTSA safety recalls have been issued for this vehicle. Contact your dealer to check if your vehicle is affected.
EQUIPMENT:OTHER:OWNERS/SERVICE/OTHER MANUAL
General Motors has decided that certain 2027 Chevrolet Bolt EV, 2025-2026 Cadillac OPTIQ, Chevrolet Colorado, Equinox EV, GMC Canyon, 2026 Buick Enclave, Envision, Cadillac CT5, Escalade, Escalade ESV, Escalade IQ, Escalade IQL, LYRIQ, VISTIQ, Chevrolet Blazer EV, Corvette Convertible, Corvette Coupe, Corvette Convertible E-Ray, Equinox, Silverado 1500, 2500, 3500, Silverado EV, Suburban 1500, Tahoe, Traverse, GMC Acadia, Hummer EV Pickup, Hummer EV SUV, Sierra 1500, 2500, 3500, Sierra EV, Terrain, Yukon, and Yukon XL vehicles. The radio may not have been set to the correct status to download the electronic owner's manual during production. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard number 208, “Occupant Protection.”
Remedy: Dealers will reset the vehicle radio, which will facilitate automatic download of the electronic owner’s manual, free of charge. Owner notification letters are expected to be mailed April 13, 2026. Owners may contact GM customer service at 1-866-467-9700, Chevrolet customer service at 1-800-222-1020 or Cadillac customer service at 1-800-333-4223. The manufacturer's number for this recall is N252540430. Vehicle Identification Numbers (VINs) involved in this recall became searchable on NHTSA.gov on February 26, 2026.
Data provided by the National Highway Traffic Safety Administration (NHTSA).
Frequently Asked Questions
What does high input mean for P0179?
High input means the sensor is reporting a voltage above what the ECM expects, typically due to a wiring fault or a sensor that has failed in a way that produces an abnormally high signal.
Can bad fuel cause P0179?
Bad fuel alone typically does not cause a high input code. This is almost always an electrical issue with the sensor or its wiring.
Community Fix Reports
Community reports are user-submitted and not verified by Auto AI Buddy. Results may vary.
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