Yup. In this case a lean code and a high voltage code mean two different things. With a lean code the oxygen sensors are working and they're just reporting what they're seeing. That's where your fuel pressure could be an issue. The high voltage code means there's something wrong with the way the sensor is working which means a wiring problem about 90 percent of the time.
Also be aware only the front O2 sensors measure the way the engine is running and they should switch between rich and lean about two times per second. Your code is for the second sensor which is behind the catalytic converter. That one only monitors the efficiency of the converter meaning how well it stores oxygen during the lean pulses and mixes with the extra fuel during the rich times and burns it. If the converter is doing its job the rear sensor will switch between rich and lean perhaps once a minute. Low fuel pressure might trigger a lean code but that would just reference the side of the engine, not a particular sensor. A lean code won't be set by a rear sensor. He will set a converter efficiency code when it sees no change taking place in the composition of the exhaust gas. The way it knows that is by the switching rate between rich and lean. As the converter's efficiency decreases, less and less change takes place as the gases pass through it. The switching rate of the rear sensor will increase because it is matching the switching rate of the front sensor. The unburned gases going into the converter are the same as the gases going out so the sensors switch between rich and lean at the same rate. It's that rear sensor's switching rate that the computer looks at to determine when to set a converter efficiency code.
The high voltage code you got suggests the catalytic converter is most likely working fine but the sensor is unable to monitor it.
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Saturday, July 20th, 2013 AT 2:50 PM