Skip to contentGarageFix
Plans and pricingFor mechanics
Sign in
← All fault codes

OBD-II · Engine and powertrain (P)

P0406

EGR sensor A circuit high

What it means

The EGR valve position sensor (usually built into the EGR valve) signal is above 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
01open sensor ground
02signal short to voltage
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).