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DTC P0407

10.06.2024
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P0407
Vehicle engine and/or automatic transmission
Code: P0407 - Exhaust gas recirculation (EGR) valve position sensor B – low input

The error code P0407 means that the Engine Control Module (ECM) has detected a low voltage signal from the Exhaust Gas Recirculation (EGR) valve position sensor, labeled as "Sensor B". This sensor tells the ECM how open or closed the EGR valve is. If the signal is too low, the system triggers this code.

The EGR system helps reduce harmful emissions by returning part of the exhaust gases into the intake to lower combustion temperatures.

Causes

  • Faulty EGR valve position sensor (Sensor B).
  • Damaged or loose wiring to the sensor.
  • Corroded or dirty connector.
  • EGR valve stuck in the closed position.
  • Faulty engine control module (rare).

Symptoms

  • Check Engine light is on.
  • Rough idle.
  • Hesitation when pressing the accelerator.
  • Increased fuel consumption.
  • Strong exhaust smell.

In some cases, the car might drive normally except for the warning light.

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How to Diagnose

  • Use an OBD-II scanner to read the code.
  • Inspect the wiring and connector for damage or corrosion.
  • Use a multimeter to check the voltage from the sensor (should be between 0.5–5V).
  • Check if the signal changes when the EGR valve moves.
  • If needed, test the sensor by replacing it with a known good one.
dtc p0407

How Common Is This Error

P0407 is not the most common error, but it can appear in cars with high mileage or those used mostly for short city trips. Lack of EGR maintenance may also lead to this issue.

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How Serious Is It

This code doesn’t cause immediate engine failure, but:

  • Emissions increase.
  • Fuel efficiency may drop.
  • Other related errors may appear later.

It’s safe to drive for a short time, but better to fix it soon to avoid bigger problems.

Repair

  • Clean or replace the EGR valve position sensor.
  • Fix or replace damaged wiring or connectors.
  • Clean or replace the EGR valve if it doesn’t move properly.
  • Clear the code with a scanner and test again to confirm the fix.

Conclusion

The P0407 code means the ECM is getting a low signal from the EGR valve position sensor. This affects the EGR system’s ability to work properly. Fixing it early is usually easy and prevents more serious engine issues. If you have a scanner, you can diagnose it yourself — or visit a repair shop for help.

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OBD P0407 code analysis and solutions

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