P1491 ACURA, HONDA, ISUZU: EXHAUST GAS RECIRCULATION VALVE INSUFFICIENT LIFT
POST UPDATED IN June, 2023
P1491 ACURA, HONDA, ISUZU: EXHAUST GAS RECIRCULATION VALVE INSUFFICIENT LIFT
In many countries around the world, NOx emissions from diesel and gasoline vehicle engines are restricted. This is a harmful compound formed by the combustion chamber of the engines.
Manufacturers have implemented a NOx emission reduction system due to the reasons exposed above. This process is known as EGR (Exhaust Gas Recirculation). Its design achieves a proportional and controlled recirculation of engine exhaust gases into the intake air. Typically, a valve is used to control the passage of the gas, and the valve closes completely if possible.
The EGR valve includes a sensor that detects the amount of valve lift. The command value for lift is pre-stored in the PCM (Powertrain Control Module) so that gas recirculation can be optimized based on driving conditions. By comparing this command value with the output signal value of the EGR valve position sensor, the PCM adjusts the valve so that the actual lift amount equals the command value.
If the EGR Valve Position Sensor output signal value has wide differences from the commanded value in the PCM memory over a given period, it is interpreted as an EGR valve or position sensor fault, giving way to the P1491 OBDII fault code setting.
The P1491 OBD2 DTC P1491 is stored by one or more of the following reasons:
To resolve the P1491 OBDII diagnostic code, consider the following: