The P0179: Fuel Composition Sensor Circuit High Input indicates that the signal from the fuel composition sensor is reading higher than expected. This could be due to a high voltage in the circuit, a faulty sensor, wiring issues, or a malfunctioning PCM.
P0179 – Quick Overview
| Meaning | P0179: Fuel Composition Sensor Circuit High Input |
| Is it serious? | Yes, this code can be serious as it may lead to incorrect fuel management, affecting engine performance and potentially causing damage. |
| Possible causes | – High voltage in the fuel composition sensor circuit – Faulty fuel composition sensor – Wiring issues such as shorts or opens – Faulty PCM |
| How to diagnose? | – Test the fuel composition sensor for proper operation. – Check for high voltage in the sensor circuit. – Inspect the wiring and connectors for defects. – Replace or repair any faulty components. |
P0179 Meaning
The P0179: Fuel Composition Sensor Circuit High Input code means that the signal from the fuel composition sensor is higher than what is expected, which could disrupt the engine’s ability to properly manage the fuel mixture and impact performance.
Step-by-step diagnostic guide
Follow the outline procedure to diagnose this DTC by eliminating possible causes one by one.
| Action | Description | Tools Needed |
|---|---|---|
| Check for Other Codes | Use an OBD-II scanner to check if there are any other related codes present. These might give additional clues about the problem. | OBD-II Scanner |
| Test the Fuel Composition Sensor | Test the fuel composition sensor to ensure it is operating within the specified range. Compare its output to the manufacturer’s specifications. | Multimeter, Manufacturer’s Specifications |
| Check for High Voltage in the Sensor Circuit | Use a multimeter to check for high voltage in the fuel composition sensor circuit, ensuring it is within the expected range. | Multimeter |
| Inspect Wiring and Connectors | Inspect the wiring and connectors for any signs of damage, corrosion, or disconnection that could lead to high voltage readings. | Flashlight, Multimeter |
| Repair or Replace Faulty Components | Repair or replace any faulty components, such as the fuel composition sensor or damaged wiring. Ensure all connections are secure and functioning properly. | Replacement Fuel Composition Sensor, Wire Strippers, Electrical Tape |
| Clear the Code and Test Drive | After completing the necessary repairs, clear the P0179 code using the OBD-II scanner. Take the vehicle for a test drive to ensure the issue is resolved and the code does not return. | OBD-II Scanner, Vehicle Owner’s Manual |
| Recheck for Codes | After the test drive, re-scan the vehicle to ensure the P0179 code has not reappeared. If the code returns, further diagnosis may be required. | OBD-II Scanner |
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Hi, I am Juraj “Yuri” Lukacko. I got frustrated by unhelpful and scammy mechanics, so I decided to learn everything about car diagnostics myself. I test dozens of new car diagnostic tools every month along with learning new strategies to fix and customize cars. About Juraj Lukacko (Yuri)