Powertrain, generic · Auxiliary emission controls

P049D EGR A Control Position Exceeded Learning Limit

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

Exhaust gas recirculation (EGR) routes part of the exhaust back into the intake to lower combustion temperature and NOx. P049D checks the learned zero point – the fully closed position – of EGR valve A. The module learns the position sensor voltage with the valve closed, at GM during the after-run following ignition off; if the learned value lies outside a window (GM 2018: 83.5–93.5 % of 5 V, GM 2016: 16.4–25.1 %) or the values scatter too much (GM Duramax LML above 30 %), the code sets – MIL after two trips at GM, immediately after learning at Ford. Usually soot at the seat keeps the valve from closing, or a new valve was not taught in.

Likely causes

Soot or deposits at the valve seat, valve does not close fully
Position sensor A faulty or characteristic shifted
New or cleaned valve not taught in, or wrong part
Position sensor circuit fault as the primary cause

Symptoms

  • Check engine light on
  • Usually no driveability effect
  • EGR possibly switched off, rough idle if the valve stays open

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€0–800
Time0.5–3 h

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

Parts involved

egr valveegr valve position sensorengine control module

Related codes

P049EP042EP042FP0405P046CP0403

References: gsi.ext.gm.com, gsi.ext.gm.com, gsi.ext.gm.com, fordservicecontent.com.