ohm reading o2 sensor
Rennlist Member
Joined: Jul 2011
Posts: 1,762
Likes: 459
From: Millersville, MD
Using a digital meter, connect the voltmeter between the O2 sensor wire and ground.
With the engine idling, the sensor voltage should be cycling from low voltage to high voltage. The signal varies between 0 and 1 volt.
If the voltage is continually high, the air/fuel ratio may be rich or the sensor may be contaminated by RTV sealant, antifreeze, or lead from leaded gasoline.
When the O2 sensor voltage is continually low, the air/fuel ratio may be lean, the sensor may be defective, or the wire between the sensor and the computer may have a high-resistance problem
You can test the sensor's reaction by disconnecting a vac line force a lean condition and, if the sensor is working, low output voltage. Conversely, you can unscrew the burner head from a propane torch and feed propane through a big vac line (being careful not to blow yourself and your car up) to force a rich condition and continually high voltage.
With the engine idling, the sensor voltage should be cycling from low voltage to high voltage. The signal varies between 0 and 1 volt.
If the voltage is continually high, the air/fuel ratio may be rich or the sensor may be contaminated by RTV sealant, antifreeze, or lead from leaded gasoline.
When the O2 sensor voltage is continually low, the air/fuel ratio may be lean, the sensor may be defective, or the wire between the sensor and the computer may have a high-resistance problem
You can test the sensor's reaction by disconnecting a vac line force a lean condition and, if the sensor is working, low output voltage. Conversely, you can unscrew the burner head from a propane torch and feed propane through a big vac line (being careful not to blow yourself and your car up) to force a rich condition and continually high voltage.
