P0179 Code - Fuel Composition Sensor Circuit High Frequency
Quick Answer
The Fuel Composition Sensor (FCS), or Flex Fuel Sensor (service parts term), measures the ethanol-gasoline ratio of the fuel being used in a flexible fuel vehicle. Common causes include Faulty Fuel Composition Sensor (FCS) or Flex Fuel Sensor, Fuel Composition Sensor harness is open or shorted, Fuel Composition Sensor circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- P0179 indicates Fuel Composition Sensor Circuit High Frequency.
- Common causes
- Common causes include Faulty Fuel Composition Sensor (FCS) or Flex Fuel Sensor, Fuel Composition Sensor harness is open or shorted, Fuel Composition Sensor circuit poor electrical connection.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Code P0179 Description
Alcohol content information is supplied to the Engine Control Module (ECM) from the Fuel Composition Sensor. The Fuel Composition Sensor has an ignition positive circuit, a signal circuit, and a ground circuit. The Fuel Composition Sensor uses a microprocessor inside the sensor to measure the ethanol percentage and changes the output signal accordingly. The signal circuit carries the ethanol percentage via the frequency signal. The ECM provides an internal pull up to 5V on the signal circuit, and the fuel composition sensor pulls the 5V to ground in pulses. The normal range of operating frequency is between 50 - 150 Hz. The microprocessor inside the sensor is capable of a certain amount of self-diagnosis. An output frequency between 180 Hz and 190 Hz indicates that the fuel is contaminated. The Diagnostic Trouble Code (DTC) will be set when the ECM detects that the fuel composition sensor output frequency is less than 45 Hz for greater than 6s.
What are the Possible Causes of the DTC P0179?
- Faulty Fuel Composition Sensor (FCS) or Flex Fuel Sensor
- Fuel Composition Sensor harness is open or shorted
- Fuel Composition Sensor circuit poor electrical connection
- Faulty Engine Control Module (ECM)
How to Fix the DTC P0179?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
Code Tech Notes
User Submitted Video
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P0179 code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
Need more information about the P0179 code?
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Information for Specific Makes
- P0179 Buick — Fuel Composition Sensor Circuit High Frequency
- P0179 Cadillac — Fuel Composition Sensor Circuit High Frequency
- P0179 Chevrolet — Fuel Composition Sensor Circuit High Frequency
- P0179 GMC — Fuel Composition Sensor Circuit High Frequency
- P0179 Mercedes-Benz — Fuel Composition Sensor Circuit High Input
Frequently Asked Questions about P0179 Code
1. What are the common symptoms of OBDII code P0179?
- Common symptoms of P0179 include poor engine performance, rough idling, decreased fuel efficiency, and potentially a Check Engine light.
2. What does the OBDII code P0179 indicate?
- P0179 indicates a high frequency signal from the fuel composition sensor circuit, which measures the ethanol content in the fuel.
3. What are some possible causes of OBDII code P0179?
- Potential causes of P0179 include a faulty fuel composition sensor, wiring issues in the sensor circuit, poor quality fuel, or a problem with the engine control module.
4. How can I diagnose the issue causing OBDII code P0179?
- Diagnosing P0179 usually involves checking the fuel composition sensor and its wiring for any visible damage, testing the sensor's resistance, and verifying the fuel quality.
5. Can I still drive my vehicle with OBDII code P0179?
- It is not recommended to drive your vehicle with P0179 as it can lead to poor engine performance and potential damage if left unresolved.
6. How can I repair OBDII code P0179?
- Repairing P0179 typically involves replacing the faulty fuel composition sensor, repairing any damaged wiring, and resetting the trouble codes with a scan tool.
7. Is it possible to prevent OBDII code P0179 from occurring?
- To prevent P0179, it is advisable to use high-quality fuel with the correct ethanol content, perform regular maintenance checks, and address any fuel system issues promptly.
8. Can a DIY enthusiast fix OBDII code P0179?
- While some DIY enthusiasts may be able to diagnose and replace the fuel composition sensor themselves, it is recommended to consult a professional mechanic for proper diagnosis and repair.
9. Will OBDII code P0179 cause permanent damage to my vehicle?
- Prolonged driving with P0179 can potentially cause damage to the engine and fuel system, so it is best to address the issue promptly to prevent any long-term damage.
10. How long does it typically take to repair OBDII code P0179?
- The repair time for P0179 can vary depending on the exact cause of the issue, but it generally takes a few hours to diagnose, replace the sensor, and clear the trouble codes.
Discuss the causes and fixes for P0179 OBDII Code
-
Yep, I put 90 Octane *NO ETHANOL* fuel in my Flex Fuel 5.3L Suburban Z71 and the stupid thing threw a P0179 Error. I guess it expects some ethanol in the fuel, but that's a pretty stupid assumption.
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