P0409 OBD-II Trouble Code: Exhaust Gas Recirculation Sensor "A" Circuit

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

SCHEDULE P0409 DIAGNOSTIC Get a fair and transparent estimate upfront
Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0409 code

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.

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 P0409 DIAGNOSTIC Get a fair and transparent estimate upfront

check engine light logo

P0409 code definition

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.

What the P0409 code means

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.

What causes the P0409 code?

  • Faulty EGR valve
  • Open or short in the wiring harness
  • Carbon Buildup on EGR valve
  • Failed EGR solenoid or position sensor

What are the symptoms of the P0409 code?

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.

How does a mechanic diagnose the P0409 code?

  • 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

Common mistakes when diagnosing the P0409 code

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.

How serious is the P0409 code?

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.

What repairs can fix the P0409 code?

  • Replacing the EGR valve
  • Decarbonizing the EGR valve
  • Repairing or replacing the wiring harness
  • Replacing the EGR solenoid
  • Replacing the EGR position sensor

Additional comments for consideration regarding the P0409 code

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.

Need help with a P0409 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
P0409
Check Engine Light

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

SCHEDULE P0409 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

3,636

Rating Summary
3,315
161
42
24
94
3,315
161
42
24
94

Chris

13 years of experience
397 reviews
Chris
13 years of experience
Professional and excellent. Highly recommended, no nonsense guy.
2002 DODGE RAM 2500 VAN - CHECK ENGINE LIGHT IS ON - SAN FRANCISCO, CALIFORNIA

Lucas

18 years of experience
767 reviews
Lucas
18 years of experience
Thank you Lucas for being patient and explaining everything to myself and my father. It took a bit of time to translate everything but he was happy with the service. You are very kind, helpful and professional! I hope to work with you again in the future! Please take care~
1999 HONDA ACCORD - CHECK ENGINE LIGHT IS ON - LOS ANGELES, CALIFORNIA

Gregory

28 years of experience
141 reviews
Gregory
28 years of experience
Greg was on time, very personable and got right to work. Would use him again. appreciated the fact he took the time to familiarize himself with the engine light codes for my 1993 Ford before he came to the appointment.
1993 FORD E-350 ECONOLINE CLUB WAGON - CHECK ENGINE LIGHT IS ON - DENVER, COLORADO

Manuel

29 years of experience
162 reviews
Manuel
29 years of experience
A true professional mr Sanchez took the time to explain what he was doing and what he plans on doing to fix my issue his knowledge about my Volvo was impressive. :-)
2003 VOLVO S60 - CHECK ENGINE LIGHT IS ON - COSTA MESA, CALIFORNIA

More related articles

How to Get a Louisiana Driver's Permit
s licensing program. The first step in this program is to obtain...
Veteran and Military Driver Laws and Benefits in New Mexico
The state of New Mexico offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...

Related questions

Q: Check Engine Light is on, trouble codes P0001 and P0006 are showing.

The fuel shut off valve is a solenoid that is controlled primarily by the shut off relay. The message you are receiving is telling you the circuit has low voltage. This means the solenoid is not energizing the way it...

Q: Got a trouble code P0171.

The purpose of the No. 2 sensor is to monitor the efficiency of the catalytic converter. Consequently, if everything is functioning correctly, the No. 2 sensor is supposed to report a constant voltage. If the No. 2 sensor waveform mimicked...

Q: My vehicle runs or idles rough. I was told that is normal, is it? And what are the signs of the transmission going out?

With a vehicle as new as yours, the likelihood of a transmission issue would be fairly slim unless damage has been done. The clanking and the rough idle may be the cause of the jerking motion. You should turn your...

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