Powertrain, generic (extended)

P2679 Coolant Degassing Valve Control Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P2679 indicates that the control line of the switched valve in the coolant vent path to the expansion tank reads too low. Usually the wire is grounded somewhere, or the solenoid has shorted turns; with a low-side driver the valve may then stay energised regardless of the command. The engine controller compares the line voltage with the state it set. Dodge lists P2679 among the fault codes that the reprogrammed engine controller of the 2004–2006 Sprinter can newly store under emissions recall T21, but the recall text gives no description of the circuit. Otherwise no maker explains P2679 publicly. CARB requires such circuit checks for controlled cooling components. A valve held in one state can slow warm-up or hinder venting.

Likely causes

Control wire shorted to ground
Shorted turns in the degassing valve solenoid
Coolant or water leaking into the valve connector

Symptoms

  • Check engine light or stored code
  • Slow warm-up
  • Coolant level fluctuations in the expansion tank

Repair estimate

DifficultyMediumDIY possible
Parts and labour€40–400
Time0.5–2 h

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

Parts involved

coolant degassing valvesolenoidwiring harness

Related codes

P2678P2680

References: law.cornell.edu, mahle-aftermarket.com, static.nhtsa.gov.