GM 12559850 Sensor,Heated Oxygen

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When servicing the oxygen sensor, the permanently attached pigtail and connector should not be removed. Grease, dirt, and other contaminants should be kept away from the electrical connector and the louvered end of the sensor. Cleaning solvents should not be used on the oxygen sensor. The sensor should not be dropped or roughly handled. The silicone boot must be installed correctly to prevent melting and ensure proper operation.

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

The engine coolant temperature (ECT) sensor is a thermistor that changes resistance with temperature. To check it, measure the resistance while cold and warm, and ensure the reference voltage from the PCM is around 5.0 volts.

The checking procedures for various engine sensors and components are as follows: The engine coolant temperature (ECT) sensor is a thermistor that changes resistance with temperature, and a failure in the circuit can trigger trouble codes. To check it, measure the resistance while cold and warm, and ensure the reference voltage from the PCM is around 5.0 volts. The manifold absolute pressure (MAP) sensor monitors intake manifold pressure changes and varies its voltage output accordingly. 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 intake air temperature (IAT) sensor acts as a thermistor, and you can measure its resistance at different temperatures to ensure it changes as expected. Also, monitor the IAT sensor using a scan tool to verify its performance. The oxygen sensor in the exhaust monitors oxygen content, and you can check its millivolt signal while the engine warms up. Inspect the oxygen sensor heater and ensure it receives proper voltage. The vehicle speed sensor (VSS) provides speed data to the PCM and can be checked for reference voltage. The camshaft sensor and crankshaft sensor, depending on the engine type, should be checked for resistance and proper signal output. Finally, the knock sensors detect engine knock and should be checked for reference voltage and resistance. If any component fails these checks, replacement may be necessary.