P0405 OBD-II Trouble Code: Exhaust Gas Recirculation Sensor Circuit A Low

Our certified mechanics come to you · 12-month, 12,000-mile warranty

SCHEDULE P0405 DIAGNOSTIC Get a fair and transparent estimate upfront
Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0405 code

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 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.

Cars Estimate Credit towards follow-up repair Earliest Availability
Ford$70.00$30.00
Toyota$70.00$30.00
BMW$70.00$30.00
SCHEDULE P0405 DIAGNOSTIC Get a fair and transparent estimate upfront

check engine light logo

P0405 code definition

Exhaust Gas Recirculation Sensor Circuit A Low

What the P0405 code means

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.

What causes the P0405 code?

  • 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.

What are the symptoms of the P0405 code?

  • 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.

How does a mechanic diagnose the P0405 code?

  • Scans codes and documents the freeze frame data in order to verify the problem
  • Clears the engine codes and road tests to verify concern and codes comes back
  • Monitors the EGR sensor pid on a scanner to see if the sensor indicates the valve is in the correct closed position or the sensor voltage return is below specifications
  • Removes the EGR sensor connector and checks for corrosion in connector and cleans if needed
  • Checks the connector if the 5 volts reference is getting to the sensor connection
  • Connects the sensor reference voltage and signal return pins together and checks the scanner to show reference voltage on EGR sensor pid
  • Replaces the EGR sensor or repairs wiring as needed then rechecks system for proper readings

Common mistakes when diagnosing the P0405 code

  • 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

How serious is the P0405 code?

  • 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.

What repairs can fix the P0405 code?

  • Replacing the EGR position sensor after the wiring is checked to be okay
  • Repairing the wiring short to the EGR position sensor or connector signal return
  • Repairing an open in the voltage reference to the EGR sensor

Additional comments for consideration regarding the P0405 code

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.

Need help with a P0405 code?

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.

trouble codes
Check Engine Light
P0405

Fast and easy Check Engine Light is on Inspection service at your home or office.

SCHEDULE P0405 DIAGNOSTIC
Get a fair and transparent estimate upfront

Recent Check Engine Light is on Inspection reviews

Excellent Rating


YourMechanic Check Engine Light is on Inspection Service

Average Rating

4.5/5

Number of Reviews

3,815

Rating Summary
3,485
164
43
24
99
3,485
164
43
24
99

Stefan

14 years of experience
366 reviews
Stefan
14 years of experience
Great service! Turned out to be the gas cap was not tightened hard enough when I last filled up. Check engine gone!
2002 TOYOTA PRIUS - CHECK ENGINE LIGHT IS ON - MOUNTAIN VIEW, CALIFORNIA

Ben

38 years of experience
883 reviews
Ben
38 years of experience
Found real issue with my car! Thanks!
2004 LEXUS GS300 - CHECK ENGINE LIGHT IS ON - HOUSTON, TEXAS

Noe

33 years of experience
525 reviews
Noe
33 years of experience
Noe was professional, knowledgeable and friendly. However, he never told I would be charged for our discussion. Only after the fact I notice I was charged $80 without every agreeing to it. I will not pay for this unagreed charge.
2004 BMW 530I - CHECK ENGINE LIGHT IS ON - MERCER ISLAND, WASHINGTON

Justin

17 years of experience
42 reviews
Justin
17 years of experience
Great and experience mechanic, friendly
2008 NISSAN VERSA - CHECK ENGINE LIGHT IS ON - CHANDLER, ARIZONA

More related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
Insurance Requirements for Car Registration in Kentucky
The Kentucky Transportation Cabinet requires that all drivers in Kentucky carry liability automotive insurance, or “financial responsibility” in order to operate a vehicle legally and maintain vehicle...

Related questions

Q: My car has trouble code P0745, do I need to replace the solenoid?

Diagnostic Trouble Code P0745 refers to out of range voltage at a solenoid-operated valve that regulates hydraulic pressure in the transmission based on outputs from the Transmission Control Module (TCM). Code P0745 is set when the TCM sees an out...

Q: Check engine light is illuminated and the car is not starting

Hey there, thanks for writing in. In the future, please include the code number. There are several codes that this system can set. If you have a crank sensor code, this will cause your car to not start. The...

Q: P0404, P0405, P0171, P0174

Hello. Thank you for writing in. Due to the p0405 code, you will want to start by replacing the sensor. This is typically easier and cheaper than replacing the EGR unit all together. If the light continues to illuminate, then...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1-800-701-6230 · hi@yourmechanic.com