Cadillac 12559850 Sensor,Heated Oxygen

The oxygen sensors in the exhaust system are placed to monitor exhaust gas stream oxygen content. Oxygen sensors are three in number. The two upstream sensors are located on the front and rear exhaust manifolds. The downstream sensor is located behind the catalytic converter. With each of these, varying in between 100 millivolts and 900 millivolts is produced by reaction of the respective oxygen content in the exhaust. The ECM uses this output voltage to determine the ideal air/fuel mixture. Controlling fuel injectors pulse width, the ECM changes air-fuel mixture ratio. To enable the catalytic converter operate at maximum efficiency, an ideal mixture consists of 14.7 parts of air to one part of fuel that will minimize exhaust emissions using it for oxidation purposes during chemical reactions on its surface which can also provide enough heat for complete combustion of unburned elements in order not to produce such pollutants again as nitrogen oxides (NOx). It is important that oxygen sensor remains hot when functioning properly; moreover within this initial period known as warm-up stage ECM operates under open loop control strategy. Four things must be right for proper functioning of an O2 sensor; Electrically speaking Outside air provision Right operating temperatures Unleaded gasoline As you work on your oxygen sensor do keep these things in mind too!! The unit has a permanent connection with a pigtail and connector which must not be removed from it because it can only cause damage or prevent normal operation from taking place so do not even try it! Keep grease, dirt and other foreign materials away from both electrical connector and louvered end of this device. Solvents can never be used to clean any kind of a thing from them! Do not drop or otherwise mishandle Sensor. For proper operation, silicone boot should be properly installed so as not to melt down or distort while doing its job correctly. Remove battery negative cable.

The knock sensors detect engine knock. To check them, you should check for reference voltage and resistance.

The oxygen sensor in the exhaust monitors oxygen content. To check it, you can check its millivolt signal while the engine warms up. It is also important to inspect the oxygen sensor heater and ensure it receives proper voltage.

The manifold absolute pressure (MAP) sensor monitors intake manifold pressure changes and varies its voltage output accordingly. To check it, you should check the reference voltage and signal voltage with the ignition on and engine off, and observe voltage changes as the engine's vacuum changes.