Exhaust Gas Recirculation Sensor A Circuit Low
The P0405 code means the vehicle's onboard diagnostic system has detected: Exhaust Gas Recirculation Sensor A Circuit Low. This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- moderate
- Estimated cost
- $100 - $400 (parts and labor)
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Common Symptoms
- Check Engine Light illuminated
- Rough idle
- Engine pinging or knocking
- Poor acceleration
- Failed emissions test
Probable Causes (Ranked by Likelihood)
- Faulty EGR position sensor Very High
- Short to ground in EGR sensor signal wire High
- Corroded EGR sensor connector Moderate
- ECM internal fault on EGR sensor input Low
Common Fixes by Vehicle
What techs usually find when diagnosing P0405 on specific vehicles — tap your vehicle for the fix and the exact part:
2004-2014 Ford F-150/Explorer 4.6L/5.4L easy DIY
P0405 means the EGR valve position sensor is reading lower than expected. On Ford trucks, the DPFE (differential pressure feedback EGR) sensor fails frequently. The sensor is mounted on the firewall with two rubber hoses connecting to the EGR tube. Replace with an OE-quality Motorcraft unit (updated design). Also clean the EGR valve passages with carb cleaner. Confirm the exact part for your year and engine with a retailer's fitment lookup or your VIN before ordering - these applications split by engine and build date.
Labor: 20-30 min2010-2020 Chevrolet Silverado/Express 4.8L/5.3L/6.0L moderate DIY
On GM V8 engines, P0405 is typically caused by heavy carbon buildup on the EGR valve pintle preventing full movement, which causes the position sensor to read low. Remove the EGR valve and clean carbon deposits with a wire brush and carb cleaner. If the valve still reads low with a scan tool commanding it open, replace with an OE-quality ACDelco unit. Confirm the exact part for your year and engine with a retailer's fitment lookup or your VIN before ordering - these applications split by engine and build date.
Labor: 30-45 min2003-2015 Honda Accord/Odyssey 2.4L/3.5L moderate DIY
Honda EGR valves use a lift sensor to report position. P0405 indicates the signal wire has high resistance or is shorted to ground. Check the 6-pin connector on the EGR valve for bent or corroded pins. Also check for carbon buildup in the EGR ports in the intake manifold -- restricted flow causes the valve to read low. Replace the EGR valve if sensor is integrated.
Labor: 30 min - 1 hourFrequently Asked Questions
Can I drive with code P0405?
You can drive short distances. The ECM cannot properly control EGR flow without accurate sensor feedback, which may cause rough running. Avoid heavy acceleration where engine knock could cause damage.
Can I replace just the EGR sensor?
On some vehicles the position sensor is a separate component that can be replaced individually. On many modern vehicles, the sensor is integrated into the EGR valve and the entire assembly must be replaced.
What voltage should the EGR sensor read?
With the EGR valve fully closed, the sensor typically reads 0.5-1.0V. Fully open, it should read 4.0-4.5V. P0405 sets when the ECM sees voltage below the expected minimum.
What actually makes the computer set an EGR code?
The OBD II regulation requires the system to flag EGR when flow deviates from the manufacturer's specified rate — in either direction, too much or too little — by enough to push emissions past 1.5 times the FTP standards; and, where no EGR fault could do that, when there is no detectable EGR flow at all (Title 13 CCR 1968.2, section (e)(8.2)). Note that excess flow is a malfunction too, which is why an EGR code does not automatically mean a blocked passage. This is the threshold the monitor is designed around, not a description of your specific fault — the regulation says what the system must detect, not how to find it on your vehicle.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
-
Check EGR position sensor voltage on a scan tool -- should read 0.5-1.0V with valve closed
-
Inspect the EGR sensor connector for corrosion or water intrusion
-
Disconnect the sensor and check if voltage rises -- if it stays low, check wiring for short to ground
-
Verify 5V reference voltage is present at the sensor connector
-
Replace the EGR valve assembly if the sensor is integrated and tests faulty
Sources 2
This page is built from documented references. Verify against your own service info before repair work.
- California Code of Regulations, Title 13 section 1968.2 (OBD II)malfunction criteria, section (e)
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
P0405 on Diesel, EV & Equipment
The same code ID appears across other engines and platforms. The diagnostic flow varies by manufacturer — these are the platform-specific breakdowns:
Commonly Affected Vehicles
- 2001-2010 Ford F-150
- 2003-2012 Ford Explorer
- 2002-2011 Ford Ranger
- 2004-2015 Chevrolet Silverado
- 2005-2014 Chrysler 300
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