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P0409 is a diagnostic trouble code (DTC) for "Exhaust Gas Recirculation Sensor "A" Circuit". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic for $70.00. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $30.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.
P0409 is a generic OBD2 diagnostic trouble code pointing to an issue with the exhaust gas recirculation circuit. This code may be seen with other EGR codes.
The P0409 code is set when there is a malfunction in the exhaust gas recirculation sensor A circuit. Low voltage from sensor A is detected by the ECU. This causes a Check Engine Light to be shown on the dashboard.
P0409 has a few typical symptoms. In all cases the Check Engine Light will be seen on the dashboard. The vehicle may experience a lack of power and a ping noise under heavy use. In some cases no adverse symptoms are noticed other than the Check Engine Light.
Hooks up a scan tool tool to the DLC port on the vehicle and checks for any history, pending, or current codes.
Checks the freeze frame data which tells the technician under what conditions the DTC was set under
Clears the codes and takes the vehicle on a test drive under similar circumstances as the freeze frame data
Performs a visual inspection on the EGR valve, wiring, and vacuum lines.
Uses a scan tool to check EGR operation
Inspects the EGR for any carbon buildup or a stuck valve
Mistakes are seen when steps are overlooked or not completed in the proper order. This can cause the replacement of parts that work fine wasting time and money.
The P0409 can be a minor annoyance but should not prevent the vehicle from being driven to a safe location once the code is seen. The EGR system is used to recycle exhaust gases back into the intake to help with emissions and will prevent the passing of OBD2 emissions while P0409 is present.
In cases where the EGR valve is stuck open or closed with carbon buildup this can be removed with cleaners which will fix the problem in some cases. A throttle body cleaner can be used to remove the carbon buildup and restore EGR valve operation.
YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.