Air induction system malfunction.
Defective throttle body.
Improper fuel pressure.
Defective Mass Airflow (MAF) meter.
Vehicle is out of fuel.
Defective Engine Coolant Temperature (ECT) sensor.
Defective crankshaft position sensor.
Defective camshaft position sensor.
Defective Engine Control Module (ECM).
Engine Light ON (or Service Engine Soon Warning Light)
The Hybrid Vehicle Electronic Control Unit (HV ECU) delivers data to the Engine Control Module (ECM) for such items as power output required for the engine (required output), estimated torque produced by the engine, engine RPM of control target RPM, and whether the engine is in start mode or not. Based on required output and target RPM, the ECM calculates a target torque that is to be produced by the engine and compares it with the estimated torque. If estimated torque is very low compared with the target torque or engine start mode continues at engine RPM or for the duration calculated by engine coolant temperature, as the abnormal condition is detected. The Diagnostic Trouble Code (DTC) P3191 is set if the following conditions continue at a fixed engine RPM or for a fixed length of time:
-Communication with HV ECU is normal.
-Engine RPM is a fixed value or more.
-Engine start mode is not active.