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OBD-II · Engine and powertrain (P)

P0405

EGR sensor A circuit low

What it means

The EGR valve position sensor (usually built into the EGR valve) signal is below the valid range.

Symptoms

  • engine warning light
  • EGR may be switched off, sometimes with reduced power
  • often no noticeable change

Likely causes, most likely first

Likely causes, most likely first
No.Cause
01signal wire short to ground
02missing 5 V reference
03failed position sensor in the EGR valve
04corroded connector

What to check, step by step

  1. 01Inspect the EGR valve connector and wiring for corrosion, oil and chafing.
  2. 02With key on, check the 5 V reference, ground and signal.
  3. 03Compare live position against the commanded position.
  4. 04If wiring is good, replace the EGR valve (the sensor is usually not sold separately).