P0407
Fix within a few daysThe Exhaust Gas Recirculation (EGR) system's position sensor 'B' circuit is reporting a voltage that is too low.
Code P0407 means your EGR sensor circuit has a low voltage. Common causes: EGR valve failure (70%), wiring issues (25%). Drivability: Yes, safe to drive, but fix soon. Repair cost: $50-$200 DIY, $150-$500 professional.
Can I Drive With P0407?
Yes, for short trips only
Essential trips under 10 miles, avoid highways and heavy acceleration. Fix within a few days.
Stop driving immediately if: Engine stalls frequently, significant power loss, or other warning lights illuminate.
Symptoms of P0407
- 1Check Engine Light is on
- 2Rough idle or stalling
- 3Reduced engine power or acceleration
- 4Engine hesitation during acceleration
- 5Increased exhaust emissions
Common Causes of P0407
Parts most likely causing this code, ranked by probability
The EGR valve's integrated position sensor has failed internally, or the valve is stuck, causing the sensor to report an abnormally low voltage.
70% of P0407 cases are fixed by replacing the EGR valve
A short to ground or an open circuit in the wiring or a corroded/damaged connector to the EGR position sensor causes the low voltage reading.
25% of P0407 cases are fixed by repairing wiring or connectors
A rare internal fault within the PCM can incorrectly interpret the EGR sensor signal as low, even if the sensor and wiring are good.
5% of P0407 cases are fixed by replacing the PCM
Check These First (Before Buying Parts)
- Visually inspect the EGR valve's electrical connector for corrosion, bent pins, or loose connections.
- Check the wiring harness for any obvious damage, chafing, or signs of rodent chewing.
- Listen for any unusual hissing sounds around the EGR valve or vacuum lines, indicating a vacuum leak.
How to Diagnose P0407
- 1Visually inspect the EGR valve and its electrical connector for damage, corrosion, or loose connections.
- 2Check the wiring harness leading to the EGR valve for any signs of fraying, cuts, or shorts to ground.
- 3Use a multimeter to test for proper voltage and ground at the EGR valve connector.
- 4If possible, use a scan tool to command the EGR valve open and closed while monitoring the sensor 'B' voltage reading.
- 5Remove the EGR valve and inspect for excessive carbon buildup that might be preventing proper valve movement or sensor operation.
P0407 on Popular Vehicles
Ford F-150
2004-2024EGR valve failure due to carbon buildup or internal sensor malfunction is a common cause for P0407 on these trucks. The valve can be difficult to access on some engine configurations.
75% fixed by replacing the EGR valve
Chevrolet Silverado
2007-2024Silverado models often experience P0407 due to a failing EGR valve. Wiring harness issues, especially near the connector, are also a known, though less frequent, cause.
70% fixed by replacing the EGR valve
Honda Accord
2003-2024While less common than on trucks, Honda Accords can trigger P0407 from a faulty EGR valve or a corroded electrical connector. Always check the connector thoroughly before replacing the valve.
65% fixed by replacing the EGR valve
Frequently Asked Questions
What does P0407 mean?
P0407 indicates that the vehicle's computer has detected a low voltage signal from the Exhaust Gas Recirculation (EGR) system's position sensor 'B' circuit. This sensor monitors the EGR valve's position.
Can I drive with P0407?
Yes, you can drive with P0407, but you should fix it within a few days. Ignoring it can lead to reduced fuel economy, increased emissions, and potentially rough engine performance. It will not cause immediate catastrophic failure.
Will P0407 clear itself?
No, P0407 will not clear itself. The underlying electrical or mechanical issue causing the low voltage signal must be repaired. Once the repair is complete, you can clear the code with a scan tool, or it will clear after several drive cycles if the fault is no longer present.
How do I fix P0407 myself?
Start by inspecting the EGR valve's electrical connector and wiring for damage. If they look good, the most common fix is replacing the EGR valve itself, as the sensor is often integrated. You may also need to clean carbon buildup in the EGR passages.
How much does it cost to fix P0407?
DIY repair costs for P0407 are typically $50-$200 for a new EGR valve. Professional repair at a shop usually costs $150-$500, including parts and labor.
P0407 keeps coming back - why?
If P0407 keeps returning, it often means the initial diagnosis was incomplete. Common reasons include a persistent wiring issue that was not fully resolved, carbon buildup in the EGR passages that was not cleaned, or a rare PCM fault that was overlooked.
Will P0407 fail emissions/smog test?
Yes, P0407 will cause your vehicle to fail an emissions or smog test. The Check Engine Light being on is an automatic failure in most jurisdictions, and an improperly functioning EGR system directly impacts exhaust emissions.
What's the difference between P0407 and P0405?
P0407 indicates a low voltage in the EGR position sensor 'B' circuit, while P0405 indicates a low voltage in the EGR position sensor 'A' circuit. Some vehicles use multiple EGR sensors or different circuits for the same sensor, and these codes differentiate which specific circuit has the fault.
P0407 on Ford F-150?
On Ford F-150s, P0407 is frequently caused by a faulty EGR valve. The valve can become clogged with carbon or its internal position sensor can fail. Inspect the valve and its electrical connector thoroughly, but expect to replace the EGR valve as the primary solution.
Questions to Ask Your Mechanic
Did you test the voltage signal from the EGR position sensor 'B' circuit?
Good answer: Yes, I measured the voltage at the sensor and it was consistently below the specified range, indicating a low circuit. I also checked the reference voltage and ground.
What did you find when inspecting the EGR valve and its wiring?
Good answer: I found the EGR valve was stuck partially open due to carbon, or the internal sensor was faulty. The wiring and connector were visually good, with no signs of corrosion or damage.
Repair Cost Estimate
DIY Repair
Parts only
$50-$200
Shop Repair
Parts + labor
$150-$500
Save $100-$300 by doing it yourself
Difficulty
intermediate
Time
1-3 hours
Intermediate - requires basic hand tools, a multimeter for testing, and potentially a scan tool to confirm the fix. Access to the EGR valve can be challenging on some vehicles.
Cost of Waiting
Ignoring P0407 leads to persistent rough idling, reduced engine power, and poor fuel economy. Continued driving with a faulty EGR system will cause your vehicle to fail emissions tests and can contribute to increased carbon buildup in other engine components, potentially leading to more expensive repairs down the road.
While You're In There...
A new gasket is essential for a proper seal when replacing the EGR valve, preventing exhaust leaks and ensuring correct system operation.
If you're accessing the EGR valve, carbon buildup is likely present. Cleaning the throttle body can improve airflow and prevent future issues.
Tools You'll Need
- Basic socket set
- Wrenches
- Screwdrivers
- Multimeter
- OBD-II scan tool
- Wire brush (for carbon cleaning)
- Gasket scraper
P0407 is a common emissions code. Most repairs involve replacing the EGR valve, which is a straightforward job for an intermediate DIYer, and your engine will run much smoother afterward.
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Your Next Steps
Step 1: Perform a thorough visual inspection of the EGR valve, its electrical connector, and the wiring harness for any damage or corrosion.
Step 2: Use a multimeter to test the voltage at the EGR sensor 'B' circuit. If the voltage is consistently low, proceed to check for shorts or open circuits in the wiring.
Step 3: If wiring is good, the most likely culprit is the EGR valve itself. Purchase a new EGR valve and a new EGR gasket for replacement.