Powertrain, generic · Auxiliary emission controls

P0405 EGR Sensor A Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

Exhaust gas recirculation (EGR) routes part of the exhaust back into the intake to lower combustion temperature and NOx. EGR sensor A is usually the valve position sensor with a 5 V supply; on Ford until about 2011 it was the DPFE differential pressure sensor. P0405 means its signal is below the lower limit – GM 2018 below 11 % of 5 V (MIL after two trips), Ford below 5 % of full scale for 4 s, Saab below 0.26 V. The cause is a short to ground or an open signal or 5 V wire. EGR position control is then switched off.

Likely causes

Wire or connector to the EGR valve open or shorted to ground
Position sensor in the EGR valve faulty (usually one unit with the valve)
Older Ford: DPFE sensor faulty
Shared 5 V reference shorted

Symptoms

  • Check engine light on
  • EGR switched off
  • Diesel: possibly reduced power
  • Otherwise hardly noticeable

Repair estimate

DifficultyEasyDIY possible
Parts and labour€30–600
Time0.5–2.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

egr valve position sensoregr valvesensor wiringengine control module

Related codes

P0406P0409P046DP0403P0404

References: gsi.ext.gm.com, fordservicecontent.com, newtonnet.co.uk, saabwisonline.com.