Monitor Conditions

The Powertrain Control Module (PCM) performs two diagnostic procedures to test the rationality of the Exhaust Gas Recirculation (EGR) sensor signal: a position rationality test and a zero reference test. The position rationality test is performed continuously when the EGR control circuit is active. The zero reference test is performed when the valve is closed, with the throttle closed and the engine RPM is below a calibrated threshold, when the PCM is attempting to learn the position of the EGR valve during the closed valve state.