p0407 exhaust gas recirculation sensor b circuit low
P0407 Exhaust Gas Recirculation Sensor B Circuit Low
Definition: This OBD2 code indicates that the Engine Control Module (ECM) has detected a low voltage signal from the Exhaust Gas Recirculation (EGR) sensor B circuit. The EGR system is responsible for recirculating a portion of the engine’s exhaust back to the engine cylinders, which helps reduce nitrogen oxide emissions and improve efficiency.
P0407 – Exhaust Gas Recirculation Sensor B Circuit Low
Typical Severity: Moderate
Common Causes
P0407 – Exhaust Gas Recirculation Sensor B Circuit Low
Common causes:
- Faulty EGR sensor
- Open or short in the wiring harness connected to the EGR sensor
- Carbon buildup in the EGR system causing restricted flow
- Issues with the EGR valve, such as being stuck open or closed
- ECU/PCM software issues related to EGR control
Common Misdiagnosis
OBD2 Code: P0407
Description: Exhaust Gas Recirculation Sensor B Circuit Low
Common Misdiagnosis: Replacing the EGR valve without checking for wiring issues or sensor faults.
Common Diagnostic Steps
OBD2 Code: P0407
Description: Exhaust Gas Recirculation Sensor B Circuit Low
- Verify the code with an OBD-II scanner and clear it to see if it returns.
- Inspect the EGR sensor wiring for damage, disconnection, or corrosion.
- Check the voltage at the EGR sensor using a multimeter. Compare it against manufacturer specifications.
- Test the EGR valve operation to ensure it’s not stuck open or closed.
- Examine vacuum hoses connected to the EGR system for leaks or blockages.
- If applicable, test and inspect any related fuses and relays in the circuit.
- Replace faulty components such as sensors, valves, or wiring as necessary based on diagnostic results.