T
ECH FEATURE By Larry Carley, technical editor
Engine Sensors Keep Everything In Check ngine sensors provide inputs for the Powertrain Control Module (PCM) so the engine computer can manage the fuel mixture, spark timing, emission functions and other control functions that are necessary to operate a modern vehicle. Without accurate inputs, the PCM can’t do its job, and engine performance, fuel economy and emissions will suffer. Sensors are monitored by the
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Onboard Diagnostic (OBD II) system, which will usually set a code and turn on the Check Engine light when a sensor problem or failure occurs. Here are a few key sensors: ● Coolant sensor — Usually located near the thermostat housing, it monitors engine coolant temperature so the PCM can change the fuel mixture and idle speed as the engine warms up. It’s input may also control
the operation of the radiator cooling fan. ● Oxygen sensors — Located in the exhaust manifold(s), the O2 sensor provides a rich/lean air/fuel mixture feedback signal for the PCM so the fuel mixture can be adjusted for lowest emissions and optimum fuel economy. On V6, V8 and V10 engines, there is usually one O2 sensor in each cylinder bank. On most four and straight six engines, there is usual-