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P0405 is a diagnostic trouble code (DTC) for "Exhaust Gas Recirculation Sensor Circuit A Low". 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. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.
Exhaust Gas Recirculation Sensor Circuit A Low
P0405 is an OBD-II generic code that the engine control module (ECM) detected the engine exhaust gas recirculation (EGR) sensor has went below its specification range. A short to ground of the sensor input to the ECM.
The ECM monitors the EGR position sensor any time the key is on and if the sensor input signal voltage drops below a specified voltage returning to the ECM, then the code is set.
The EGR sensor return is internally shorted to ground.
The EGR sensor return wiring or connection is shorted to ground.
The EGR sensor 5 volt reference voltage is open in the sensor or connection is not making contact.
The Check Engine Light will be illuminated and the code is set in ECM memory.
The ECM may open the EGR valve more than needed if voltage is too low causing a stall or hesitation on acceleration.
The engine EGR system can cause the engine to run rough, hesitate, or even stall if it is not indicating the proper EGR valve position to the ECM.
The ECM may disable the valve from opening when it sees a fault and the engine may have pre-ignition on acceleration.
Not connecting the sensor reference voltage and signal return pins together to see if all the wiring is good before replacing the EGR position sensor
Not checking the wiring harness and connection to the EGR position sensor for shorts or open circuits before replacing the EGR position sensor
The ECM may disable the EGR system and render it inoperative when this code is active.
The Check Engine Light being on causes the vehicle to fail emission testing.
The EGR position is critical for the ECM to properly control the EGR valve opening and closing, and can cause the engine to run rough and stall.
Code P0405 is triggered when the EGR position is below the ECM expected sensor position and the most common cause is the EGR sensor has an open circuit internally.
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