Powertrain, generic · Auxiliary emission controls

P0488 EGR Throttle Control Circuit A Range/Performance

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. The EGR throttle is a regulating flap ahead of the intake manifold on diesels: by closing partly it lowers manifold pressure below exhaust back pressure so that enough exhaust is recirculated, and it also helps filter regeneration and shuts off air at engine stop. It is usually a DC motor with position sensor. GM and Ford report this flap under P02E0 ff; no manufacturer document available to us uses this code. P0488 is its function check: the actual position reported by the sensor deviates from the target for too long, or the position signal is implausible – typically a coked, stiff flap or a broken gear. The flap then goes to its rest position or the engine enters limp mode, and the EGR rate cannot be controlled.

Likely causes

Flap coked by soot and oil mist (EGR plus crankcase ventilation)
Actuator gear or motor worn or broken
Position sensor in the flap faulty or implausible
Corrosion on flap or housing

Symptoms

  • Check engine light on
  • Loss of power or limp mode possible
  • Shaking when the engine is switched off
  • Filter regeneration does not complete

Repair estimate

DifficultyMediumDIY possible
Parts and labour€80–600
Time0.5–2.5 h

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

Parts involved

egr throttle valvethrottle actuatorthrottle position sensorengine control module

Related codes

P0487P02E0P02E1P0401P0402

References: law.cornell.edu, ms-motorservice.com, patents.google.com.