P0409 - EXHAUST GAS RECIRCULATION SENSOR "A" CIRCUIT
POST UPDATED IN November, 2021
Description of DTC code P0409 Generic
The diagnostic code P0409 OBDII is set because the PCM (Powertrain Control Module) finds a malfunction in the electrical control of the EGR (Exhaust Gas Recirculation) system.
The EGR system aims to introduce very precise amounts of exhaust gas into the engine during specific conditions and reduce combustion temperature. Due to this system, nitrogen oxide is reduced, and the level of pollution for the atmosphere is lowered.
The PCM is responsible for storing all input data from various sensors to determine the timing and input of exhaust gases and to reduce the formation of nitrogen oxides. When the EGR system is operating correctly, no exhaust gas will be introduced at low engine speeds when the engine is idling because it affects the combustion process. When the PCM detects a fault in the control of the EGR system which prevents effective control, this code is set. It should be noted that the Check Engine light does not turn on at the first failure.
Symptoms of fault code P0409 Generic
MIL (engine malfunction) light on.
Other codes related to the EGR system have been established.
The vehicle can be stopped.
Causes of OBD2 P0409 Generic
The error code P0409 OBD2 is set by the following
There may be some defects in the EGR Sensor
Defective EGR sensor.
Perhaps, the EGR pin is stuck in the closed position due to carbon build-up.
A lack of vacuum in the EGR
EGR solenoid in bad condition.
Possible solutions of the DTC code P0409 Generic
To solve the failures produced by the DTC code P0409 OBDII, take into account the following suggestions:
Verify that the EGR Sensor connector is not corroded. Also, check that the terminals are not bent or misaligned. If so, make repairs.
Check the vacuum line from the EGR to the solenoid, if it has problems, change it.
Check the EGR valve for excess carbon, clean it if necessary.
Check both pressure hoses. They may be corroded. If so, replace them.