Powertrain, generic (extended)

P26BD Engine Coolant Bypass Valve D Control Circuit/Open

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P26BD is the open-load or general circuit fault on the output that drives coolant bypass valve D. Ford is the documented user. Both editions of its gasoline OBD summary, 2020–2023 and 2024–2025, assign valve D to cabin heating, meaning the valve that routes engine coolant to the heater core, and set P26BD once the PCM's smart driver signals an output fault during continuous 5 s monitoring; the 2024 edition adds the extended form P26BD_13. Ford's 2014 code list for spark-ignition engines already names P26BD with the Circuit/Open wording. GM's public tables do not use P26BD. Because the valve mainly serves the heater, the usual effect is too little or uncontrolled cabin heat rather than an engine problem. P26BE and P26BF cover shorted lines.

Likely causes

Open coil or motor winding in valve D
Loose or corroded valve connector
Broken drive wire between PCM and valve

Symptoms

  • Check engine light
  • Weak or no cabin heat
  • Heater output that cannot be regulated

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–500
Time0.5–2.5 h

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

Parts involved

coolant bypass valve dsolenoidwiring harness

Related codes

P26BEP26BFP26C1P26B7

References: fordservicecontent.com, fordservicecontent.com, performanceparts.ford.com.