P0406 OBD-II Trouble Code: Exhaust Gas Recirculation Sensor "A" Circuit High

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

SCHEDULE P0406 DIAGNOSTIC Get a fair and transparent estimate upfront
Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0406 code

P0406 is a diagnostic trouble code (DTC) for "Exhaust Gas Recirculation Sensor "A" Circuit High". 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 $69.99. 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.

Cars Estimate Credit towards follow-up repair Earliest Availability
Ford$69.99$20.00
Toyota$69.99$20.00
BMW$69.99$20.00
SCHEDULE P0406 DIAGNOSTIC Get a fair and transparent estimate upfront

check engine light logo

P0406 code definition

P0406 is a general ODB2 trouble code indicating a fault within the exhaust gas recirculation EGR circuit. This code is similar to P0400, P0401, P0402, P0403, P0404, P0405, P0407, P0408, P0409.

What the P0406 code means

P0406 means that the exhaust gas recirculation (EGR) sensor A has high circuit voltage. The ECU detects this high voltage and sets a Check Engine Light. The Check Engine Light will be illuminated on the dashboard.

What causes the P0406 code?

  • Failed EGR valve
  • Excessive carbon buildup
  • Open or short in the wiring harness
  • Poor electrical connection
  • Leak in the vacuum line to EGR valve

What are the symptoms of the P0406 code?

  • In most circumstances the driver may not notice any symptoms other that then illuminated Check Engine Light.

  • Some vehicles may have a slight engine hesitation and fluctuating RPMs.

  • In rare cases the vehicle may have some pinging at higher load and engine stalling.

How does a mechanic diagnose the P0406 code?

  • Uses a scan tool to check for any history, pending and current codes

  • Notes freeze frame data, such as vehicle temperature, run time, and load when the fault occurred

  • Clears the code

  • Performs a test drive trying to duplicate the conditions from the freeze frame data

  • Performs a visual inspection for damaged or worn wiring, broken vacuum lines, and loose electrical connectors

  • Uses the scan tool to view EGR position upon startup and running and manifold pressure

  • Inspects EGR valve for carbon buildup causing it to not open and close properly

Common mistakes when diagnosing the P0406 code

Diagnosis of the P0406 code can be a simple matter or turn into a nightmare if step by step diagnosis is not performed and every step needed completed. This can cause the real problem to be over looked and unneeded repairs performed.

How serious is the P0406 code?

P0406 has a wide range of symptoms that can vary from just the Check Engine Light being on to a vehicle that won't stay running or drives poorly. In vehicles with drivability concerns care should be taken when driving.

The P0406 code should not prevent the vehicle from being driven to a safe location after the fault occurs.

What repairs can fix the P0406 code?

  • Replacing the EGR valve
  • Repairing or replacing wiring harness as needed
  • Repairing poor electrical connections
  • Replacing the vacuum line
  • Cleaning excessive carbon buildup

Additional comments for consideration regarding the P0406 code

In some cases the EGR valve and system may be able to be cleaned. There are specialized cleaners that are used to break up the carbon so it can be cleaned.

Cleaner instructions must be followed but some EGR valves may be able to have the carbon removed and work properly instead of needing replacement.

Need help with a P0406 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
P0406

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

SCHEDULE P0406 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

4,240

Rating Summary
3,884
174
45
26
111
3,884
174
45
26
111
Jose

Jose

14 years of experience
433 reviews
Jose
14 years of experience
Jose has repaired both of the cars I have a few times now. He is always generous with his knowledge, his time, and his expertise. My wife and I are always impressed with his dedication to get to the job site, and get the repair done. We already have mind to recommend him to other people we know in the area, should they have car trouble, and one of them really does, all the time.
2005 CHEVROLET EQUINOX - CHECK ENGINE LIGHT IS ON - BEAVERTON, OREGON
Theodore

Theodore

13 years of experience
814 reviews
Theodore
13 years of experience
Theodore is awesome finds the problem fast and takes care of it he saved me $160 today thanks Theodore
1998 JEEP WRANGLER - CHECK ENGINE LIGHT IS ON - REDMOND, WASHINGTON
Gerron

Gerron

31 years of experience
118 reviews
Gerron
31 years of experience
Quicker than I thought and he's truly an experienced mechanic.
2015 CHEVROLET MALIBU - CHECK ENGINE LIGHT IS ON - PORTLAND, OREGON
Brett

Brett

7 years of experience
167 reviews
Brett
7 years of experience
Brett was awesome!
2009 CHEVROLET TRAVERSE - CHECK ENGINE LIGHT IS ON - AUSTIN, TEXAS

More related articles

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...
How to Buy Fuel Treatments
Adding a fuel additive to your gas tank when you fill up is one way to clean vital engine parts of deposits, improve the performance of your engine,...
How to Get a Louisiana Driver's Permit
s licensing program. The first step in this program is to obtain...

Related questions

Q: Getting error codes P0599 and P0171. Ive cleaned the O2 sensors but have no idea where to go from here.

Hello. Code P0599 is the code for an issue with the thermostat heater control circuit, while P0171 is for a lean condition on bank 1. P0599 is set when the computer detects that there is an issue with the electronically...

Q: Check Engine code P0170

Hi there. I see you've replaced the recommended parts that supplement the error code. Another reason why your vehicle maybe not be receiving sufficient fuel is because of a clogged or obstructed fuel filter and pump. When your vehicle gets...

Q: What is the code P0406 and P0128?

The code P0406 is for the electronic gas recirculation valve high circuit input. Meaning the valves sensor is detecting a high voltage input. This can be due to carbon build up on the valve, a bad valve, or a bad...

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