P1138 - O2 Sensor Heater Circuit Low Voltage (Bank 1 Sensor 2)
P1000 - Monitor Testing Not Complete
The first code is typically caused by a grounded wire, but you need a scanner to view live data to know for sure. A grounded wire will give you a 0.0 volt reading and that code will set. If you find the voltage is higher than 0.0 volts but stays below about 0.5 volts, there's something causing a fuel / air mixture problem and the sensor and fault code are just reporting what it sees. The sensor after the catalytic converter just monitors the efficiency of the converter. It's voltage is expected to switch between below and above half a volt perhaps once or twice per minute. If it stays in one state too long, that would set a fault code related to "catalytic converter efficiency". Your code is quite different, so I'd check the wiring before I'd replace the sensor.
There are many self-tests run by the Engine Computer. The second code just means one of those tests has been suspended because two or more things are compared, based, in part on the readings from that oxygen sensor. The computer knows it can't rely on that sensor's readings so it can't use those values for comparison for other tests.
Tuesday, October 7th, 2014 AT 2:26 AM