Oxygen Sensor and diagnosis
A GM O2 sensor signal stuck at 450 mV is an indication of an open O2 sensor circuit (signal wire) or faulty O2
signal ground. The 450 mV value (GM) is called a bias voltage .
Some manufacturers employ a dedicated O2 sensor ground. Such a ground lead is attached to the engine block
or chassis and feeds an ECM O2 ground pin only. The O2 circuit is then grounded through the inside of the
ECM electronic board by this ground wire. A loss of this ground would also put the O2 sensor signal at around
450 mV, which also makes it look like an open circuit. The same holds true for Chrysler, but these use a different
O2 bias voltage, which is usually 2.00 to 4.00 volts.
sources: from-----www.diycardoctor.com/Downloads/YouTube/Section%201.pdf
signal ground. The 450 mV value (GM) is called a bias voltage .
Some manufacturers employ a dedicated O2 sensor ground. Such a ground lead is attached to the engine block
or chassis and feeds an ECM O2 ground pin only. The O2 circuit is then grounded through the inside of the
ECM electronic board by this ground wire. A loss of this ground would also put the O2 sensor signal at around
450 mV, which also makes it look like an open circuit. The same holds true for Chrysler, but these use a different
O2 bias voltage, which is usually 2.00 to 4.00 volts.
sources: from-----www.diycardoctor.com/Downloads/YouTube/Section%201.pdf