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2005 Chevrolet Malibu Fuel Level Sensor Failure: OBD2 Codes C0561 and C0121 Explained

Model: 2005 Chevy Malibu Fault Code: C0121 Posted: 2015-09-05 14:11

Hello Auto Enthusiasts, I own a 2005 Chevrolet Malibu LS with a V6 3.6L engine, and I'm experiencing issues related to the fuel level sensor. The car is currently displaying two OBD2 diagnostic codes: C0561 and C0121. Can anyone clarify what these codes mean in simple terms? Specifically: - Code C0561 indicates 'Invalid serial data received' — this suggests that the vehicle's fuel level sensor is sending corrupted or inconsistent signals to the engine control module (ECM). - Code C0121 refers to a 'Valve Relay Circuit History' issue, which may point to an electrical problem in the relay circuit associated with the fuel system. Given these issues, how much would it cost to replace the fuel level sensor? If replacement isn't feasible right now, can I safely drive the car for short daily commutes (about 5 miles each way, Monday through Friday)? Additionally, is there a simple fix — like replacing a relay in the relay console — that could resolve these issues without needing a full sensor replacement? Thanks for your help! Jamier, The Scientist

Related fault codes
C0121C0561
Comments (3)
Anonymous 2015-09-06 16:13

Please provide complete vehicle details: year, make, model, engine type. Also confirm if the ABS warning light is on — OBD2 C-series codes (like C0561 and C0121) are typically related to the anti-lock braking system, not fuel sensors. This helps determine whether the issue is with the brake system or another component.

Anonymous 2015-09-06 20:20

Vehicle: 2005 Chevrolet Malibu LS, V6 3.6L engine. This model has known issues with fuel level sensor and relay-related OBD2 codes.

Anonymous 2015-09-06 20:26

Could you confirm all active diagnostic codes? What specific symptoms are present with the fuel level sensor — such as inaccurate gauge readings or warning lights? This will help determine if a sensor replacement or electrical repair is needed.