Posts Tagged: rich fuel condition
What Does Negative Fuel Trim Mean? Expert Diagnosis Guide
Negative Fuel Trim: What It Means, What Causes It, and How to Fix It Fast Quick Summary A negative fuel trim <-10% means the engine computer is subtracting fuel because the engine is running too rich. Running rich can be caused by too much fuel or insufficient air entering the combustion process. The most common causes of negative fuel trim include: • Leaking fuel injectors • High fuel pressure • Faulty sensors • Restricted airflow, • Evaporative system issues. Fixing negative fuel trim requires identifying why the engine is rich … Read More
Common Causes of a P0138 Code: O2 Sensor High Voltage
P0138 Code: Causes, Symptoms, and Fixes Explained Quick Summary When I diagnose a P0138 code, I know the engine computer is detecting a high-voltage signal from the rear oxygen sensor (Bank 1, Sensor 2). That usually means the sensor is reporting a consistently rich condition—or the circuit itself is faulty. In most cases, the root cause is a • failing O2 sensor • wiring issue • exhaust leak, • or a true rich-running condition. The fix comes down to verifying sensor data, checking wiring integrity, and confirming whether the engine … Read More