Powertrain, generic (extended)

P23E6 EGR C Control Stuck Closed

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

With P23E6 the module concludes that EGR valve C does not open when commanded and stays at or near its closed stop. The consequence is the reverse of P23E5: the engine runs smoothly, but the exhaust share from this path is missing, combustion temperature and NOx go up, and a petrol engine may knock more readily. Typical reasons are a valve glued shut by soot, a seized shaft, a stripped drive gear or a motor that no longer delivers enough torque against the deposits. The counterparts for valves A and B are P042F and P045F; GM's 2018 diesel tables group P042F with P042E as position deviation faults. No manufacturer documents P23E6 publicly; CARB requires EGR systems to be monitored for insufficient flow and faulty control. Low flow from this path is P23E7.

Likely causes

Valve C glued shut by soot
Seized shaft or stripped drive gear
Actuator motor too weak to break the valve free

Symptoms

  • No change in driving, but higher NOx
  • Possible knocking on petrol engines
  • Warning lamp

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€100–1,200
Time0.5–4 h

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

Parts involved

egr valve c

Related codes

P23E5P23E7P23E2P042FP045F

References: gsi.ext.gm.com, law.cornell.edu.