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P0407: Exhaust Gas Recirculation Sensor B Circuit Low

Severity: Medium Arrange diagnosis soon. If the engine stalls, surges severely, or pings under load, avoid continued driving until the cause is checked.

What does P0407 mean?

The EGR sensor B feedback circuit is below its electrical limit. B identifies a feedback channel defined by the manufacturer, not bank 2 or necessarily a second visible EGR valve.

Generic OBD-II definition: Exhaust Gas Recirculation Sensor B Circuit Low. Confirm applicability in your vehicle service information.

Common causes

  • B signal shorted to ground
  • Missing sensor reference or bad connector
  • Failed B feedback sensor

Symptoms

  • Check engine light
  • Possible rough idle or surging
  • Sometimes no noticeable driving symptom

Diagnostic focus

Do not use the A-channel connector pinout without checking the diagram. A shared reference fault may affect both feedback channels, while a local fault may only affect B.

Can I keep driving with P0407?

Severity: Medium Arrange diagnosis soon. If the engine stalls, surges severely, or pings under load, avoid continued driving until the cause is checked.

If the check engine light is flashing or the car runs badly, stop driving and have it checked.

Typical fixes

  • Identify channel B from service information
  • Test its reference, return, and low signal
  • Check feedback after repairing a verified circuit fault

Related codes

P0405
Exhaust Gas Recirculation Sensor A Circuit LowP0408
Exhaust Gas Recirculation Sensor B Circuit HighP0409
Exhaust Gas Recirculation Sensor A Circuit

Sources & review

Definitions and diagnostic background checked 2026-11-06. Generic guidance, not a substitute for the service procedure for your exact year, engine, and transmission.