Pontiac 19178930 Sensor Asm,Heated Oxygen

The oxygen sensor is a device that produces a voltage when exposed to oxygen in the exhaust gases. It is in the exhaust system and can be heated internally for faster reaction. The sensor produces a voltage between zero and one volt, with a low voltage indicating a lean mixture and a high voltage indicating a rich mixture. The stoichiometric air to fuel ratio causes the voltage to fluctuate.

The oxygen sensor is mounted in the exhaust manifold and its function is to measure the oxygen content of the exhaust gas stream and to produce an output voltage in the range 0.1 volt to 0.9 volts where a low voltage corresponds to a high oxygen concentration, or rich mixture, to a low voltage corresponding to a low oxygen concentration, lean mixture. The ECM uses this variable voltage to adjust the particulars of the fuel-to-air mixture with an ideal balance of 14.7 air to 1 fuel in order to obtain the least exhaust emission and optimized catalytic converter functioning. The sensor does not generate voltage below the typical operating temperature of about 600-degrees F, so the ECM runs in open-loop during warm-up. If the engine stays normal temperature and the sensor provides a constant voltage of 0.35 to 0.55 volt, and the TPS shows it is not at idle a Code 13 is stored. A failure to operate for two minutes or more or low voltage or short circuit produces the Code 44, while a high voltage signal produces the Code 45. In these case the ECM drops out to a preset value to fuel delivery rather than using feedback from the sensor. For correct operation of the sensor, its electric contacts have to be clean and well-connected to enable electricity flow, there has to be a proper air circulation around the sensor so that the operating temperature is reached and the fuel used contains no lead. Several precautions should not be made during servicing among them being, do not remove the permanently attached pigtail and connector, do not allow contaminants to come near the electrical connector and the sensor end, do not clean with solvents, handle the sensor tenderly and ensure that the silicon boot is well placed. when replacing the sensor it may be tight if the engine is cold and can be eased if the engine is run for a bit. The procedure includes removing the battery, lifting the car, removing the electrical connector, capturing the position of the silicone boot, unscrewing the sensor loosely, applying some anti seize compound on the threads of the sensor, putting the new sensor and tightening it, connecting the electrical connector, grounding the car and reconnecting the battery.

Various engine sensors and components have checking procedures,the engine coolant temperature (ECT) sensor is a thermistor that changes resistance with temperature, and a failure in the circuit can cause trouble codes. The resistance should be measured when cold and warm while ensuring reference voltage from PCM is around 5.0 volts for the verification. Manifold Absolute Pressure (MAP) Sensor monitors changes in intake manifold pressure then varies its voltage output accordingly. Look at the reference voltage and signal voltage with the ignition on and engine off, and observe voltage changes as the engine's vacuum changes. Intake Air Temperature (IAT) Sensor acts as a thermistor where you can measure its resistance at different temperatures to make sure it changes as expected. Also, use a scan tool to monitor the IAT sensor for performance. The oxygen sensor in exhaust detects oxygen content which you can check its millivolt signal while warming up your engine. Check whether the oxygen sensor heater has correct voltage or not. Vehicle Speed Sensor (VSS) provides speed data to PCM which can be checked for reference voltage. Depending on the type of engine, Camshaft Sensor and Crankshaft Sensor should be checked for resistance and proper signal output. Finally, Knock Sensors detect engine knock which should be checked for reference voltage and resistance. If any component fails these checks, replacement may be necessary.

When testing, only use a high-impedance (10 mega ohms) digital multi-meter to avoid shorting / shocking the PCM out. On models that are fitted with a Theftlock audio system, verify that the lock out feature is switched off before removing the battery terminal. The self-diagnosis system can only be activated by the TECH 1 SCAN tool-if that is not available, obtain the vehicle codes from a dealer or an authorized repair center. Thermistors that are resistors with varying resistance according to the temperature ought to be high when the temperature is low, and low as the temperature increases. To verify, turn on the multi-meter by selecting the ohms range, remove the harness connector and then place the test probe of the multi-meter on both terminals of the sensor. After checking resistance, check for reference voltage from computer it should be 5.0 volts with ignition switch on. Electrical rotary devices such as the throttle position signal should be tested by back probing the harness connector and noting voltage changes when the signal arm is varied. Intake manifold pressure/vacuum sensor monitors the pressure variation at the intake manifold and should display voltage from below 2.0V when the engine is idle to above 4.0V WOT. Magnetic reluctance sensors including crankshaft and vehicles speed sensors include observing fluctuation of voltage by using AC volt meter when the engine is cranking or by rotating the sensor. Hall effect sensors output ON/OFF signals to the powertrain control module, and should display voltages when the engine is turned over. Dual Hall effect sensors work in the same manner, but they give two different ON/OFF signals. Oxygen sensors measure exhaust gas oxygen content with a voltage signal range of 0.1-0.9 Volts: test for millivolt signals as the engine warms. MAF sensor, records the air getting into the engine and its readout is in grams per second by use of a SCAN tool. Engine vibration is sensed by knock sensors and they generate ac output voltage which should vary when tapped. The NVLD switch lights up when the transaxle is in Park/Neutral taping various systems. The PCM acts on the acoustic knock sensors to alter engine load and the air conditioning compressor clutch for the same as well as the power steering pressure sensor to observe fluid pressure that may cause idle problems. The fuel tank pressure sensor is used during emissions checking of the pressure while the Torque Converter Clutch system in automatic transaxles operates to lock the torque converter at cruising speed while allowing minor adjustments to fuel saving; it requires tools that are special to check and repair.

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.

You should be careful to avoid damaging or removing the pigtail or electrical connector, as this will render the sensor useless.

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.

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.