Theory Of Operation

WARNING: This page is about a different car, the 2020 Jeep Renegade. However, it is still accessible from the selected car via links, so may be relevant.

The Powertrain Control Module (PCM) monitors the pulsations within the intake manifold caused by the valve train opening and closing during cranking. The diagnostic for DTC P1523 is specifically looking for a calibrated minimum number of pulsations measured by the Manifold Absolute Pressure (MAP) Sensor during engine cranking before startup in order to verify that the Variable Valve Actuator (VVA) Assembly is operating properly. If the diagnostic does not pass it is assumed that the valves are not opening and closing as they should, and therefore an oiling issue must exist. The VVA Solenoids are monitored separately.

Although this diagnostic is designed to identify an oiling issue with the VVA Assembly, a mechanical issue in the valve train could also cause this diagnostic to fail. A faulty MAP Sensor can also cause this code to set. If the MAP Sensor is missing its 5-Volt Reference, the sensor may be stuck mid-range. This can cause the sensor to be sending a reading, but not registering actual pressure within the Intake Manifold. The MAP Sensor could also be plugged or restricted due to contamination or debris such as oil or carbon, and should be inspected for such conditions.