Fuel Level Output Circuit Malfunction
The P0656 code indicates a malfunction in the fuel level output circuit, which is responsible for sending the fuel level signal from the fuel tank sending unit to the engine control module (ECM) or instrument cluster. This circuit typically includes the fuel level sensor, wiring, connectors, and the ECM. When the ECM detects an abnormal voltage or resistance in the circuit, it sets this code. Common causes include a faulty fuel level sensor, damaged wiring or connectors, or a malfunctioning ECM. Symptoms may include an inaccurate fuel gauge, the check engine light illuminating, or the fuel gauge reading empty or full constantly.
1. Most Common Causes
- Faulty fuel level sensor
- Damaged wiring or connectors in the fuel level circuit
- Corrosion or poor electrical connections
- Malfunctioning engine control module (ECM)
2. Symptoms You Will Notice
- Inaccurate fuel gauge reading
- Check engine light illuminated
- Fuel gauge stuck on empty or full
- Fuel gauge fluctuating erratically
3. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for any related codes.
Step 2: Visually inspect the fuel level sensor wiring and connectors for damage, corrosion, or loose connections.
Step 3: Test the fuel level sensor resistance with a multimeter and compare to manufacturer specifications.
Step 4: Check the voltage signal at the ECM connector to verify proper circuit operation.
Step 5: If all else is good, consider replacing the fuel level sensor or ECM as needed.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
Yes, it is generally safe to drive, but you may not have an accurate fuel gauge, which could lead to running out of fuel unexpectedly.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for diagnosis and repair, depending on the cause and labor rates.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.