Pcm Code E45, Oxygen (O2) Sensor Rich Exhaust Signal: Description

PCM provides a .45-volt reference signal to O2 sensor on circuit No. 412. When O2 sensor is cold, less than 392°F (200°C), output voltage will be about .45 volt. PCM will keep system in "open loop" operation. When warm, a properly operating O2 sensor will drive .45-volt reference lower (less than .45 volt) to indicate a lean mixture or higher (greater than .45 volt) to indicate a rich mixture. O2 sensor signal voltage will swing from rich to lean rapidly. This happens at least once every 2 seconds if PCM is in good control of air/fuel mixture.

When PCM determines O2 sensor signal is not at .45 volt (cold voltage), it will send system into "closed loop" operation. In "closed loop" operation, PCM will meter fuel into engine based on O2 sensor readings.

Code E45 is designed to set if O2 sensor stays at rich voltage for more than 51 seconds during test conditions. Code E45 will set when O2 sensor circuit is faulty or air/fuel ratio is actually rich due to fuel control or emissions system fault.