What does fault code 118001 (mixture too lean) mean?
2 Answers
Fault code 118001 indicating a too lean mixture is mainly caused by low fuel pump pressure, excessive carbon deposits leading to dirty/clogged fuel injectors, or control circuit malfunctions. Causes of lean mixture: Low fuel pump pressure; Excessive carbon deposits causing dirty/clogged fuel injectors; Faulty intake pressure sensor signal; Various intake sensors failing to accurately detect intake volume, resulting in insufficient fuel injection; Failure of oxygen sensor closed-loop control; Excessive adjustment of main metering needle, blocking the orifice; Fuel level in float chamber too low; Loose fuel pipe connections, fuel/air leaks, or pipe damage/dents/blockages; Excessive clearance in fuel pump rocker arm or overly thick gasket between fuel pump and cylinder block; Poor sealing of fuel pump valves, diaphragm leaks, or excessively dirty filter screen causing insufficient fuel supply. Function of automotive fault codes: Automotive fault codes are diagnostic codes generated by the vehicle's ECU when malfunctions occur. These codes enable technicians to precisely identify faulty components for repair. Fault codes represent essential conditions checked in control logic to determine whether certain functions meet control requirements. If not, the function will be canceled or restricted while alerting the driver. For critical signals, backup signals will be provided as substitutes during restriction, serving as the basis for the control unit's normal operation.
Recently, my car displayed fault code 118001, and the issue of a lean fuel mixture is really giving me a headache. It means there's too much air and too little fuel in the engine, making the car feel unstable when driving and noticeably shaky at idle. When I was younger, I fixed similar problems many times. Possible causes include vacuum leaks, such as aged hoses or cracked gaskets allowing extra air to sneak into the engine; fuel system failures, like insufficient fuel pump pressure or clogged filters; or faulty sensors, such as the MAF sensor that measures airflow malfunctioning. If left untreated, not only will fuel consumption increase, but it could also lead to engine overheating or damage to the catalytic converter. So, I immediately stopped driving and took it to a professional shop for inspection. They used diagnostic tools to identify the root cause, fixed the hose issue, and resolved the problem. I recommend everyone regularly check their intake pipes to reduce such risks.
