How to Determine if an Oxygen Sensor is Faulty?
2 Answers
You can determine if an oxygen sensor is faulty by observing the color of its tip: 1. Light gray tip: This is the normal color for a functioning oxygen sensor. 2. White tip: Caused by silicon contamination, the oxygen sensor must be replaced in this case. 3. Brown tip: Caused by lead contamination; if severe, the oxygen sensor must also be replaced. 4. Black tip: Caused by carbon buildup; after addressing the engine's carbon deposit issue, the sensor's carbon buildup can usually clear automatically. Below are common faults of oxygen sensors: 1. Oxygen sensor poisoning. Ensure proper selection and installation of rubber gaskets during repairs. 2. Carbon buildup. Symptoms include increased fuel consumption and significantly higher emissions. Removing the deposits can restore normal operation. 3. Ceramic breakage in the oxygen sensor. Striking with hard objects or using strong airflow for cleaning can cause the ceramic to break, rendering the sensor ineffective. Replace the sensor promptly if any issues are detected.
I have some experience in maintaining older cars, and there are a few common signs to watch out for when it comes to oxygen sensor issues. The most obvious one is the persistent illumination of the engine warning light on the dashboard. Plugging in an OBD-II scanner usually reveals codes like P0135 or P0140, directly pointing to sensor problems. If you notice unstable engine idling, sluggish acceleration, or a sudden increase in fuel consumption—for example, if your car used to run 500 kilometers on a full tank but now only manages 400—it's time for a check. You can do a preliminary inspection yourself to see if there's any damage or excessive carbon buildup around the sensor, but it's more reliable to take it to a professional repair shop. They'll use a multimeter to check if the voltage fluctuates normally between 0.1 and 0.9 volts. Don’t delay, as this can worsen carbon buildup or affect engine longevity. Regular cleaning of the exhaust system during car washes can help prevent issues.
