98 ranger with 4.0 engine. Have replaced three of the four O2 sensors over the last several years. Engine code 1151 indicating O2 sensor on Pass side before the converter has come up again for the third time in 15 months. Could there be something else going on to cause this code?? Is there a measurement that can be made at the sensor( voltage) to confirm its functionality?? These things arent cheap....

Thanks


Coach 955

 

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Well I'm thinking maybe a vacuum leak. The vintage of this vehicle wold make the upper or lower intake manafold's gaskets, or old vacuum lines a good possibility.

Did you mean code 151????
The 151 reading says the O2 circuit voltage output for bank 2 is low.

If you had a lean mixture from an unmetered air leak, that could cause the O2 to read low output/lean.

Could be a bad electrical connection at the sensor or a bad sensor.

With the engine heated up, the O2 sensors output voltage should be between 0.1 volts, lean mixture, to 0.9 volts, rich mixture.

When the sensor is up to it's operating temperature of 600 deg F, it will normally read between 0.35 & 0.55 volts.

Hope all this helps some in isolating your problem.