Powertrain, generic (extended)

P26D5 Engine Coolant Pump Supply Voltage Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P26D5 is set when the power feed of the engine coolant pump carries a higher voltage than the system allows. No manufacturer documents this code in public. It belongs to the same supply group as P26D3 and P26D4; Ford's hybrid OBD summaries explain the supply logic on the general code, and CARB requires electrical faults of monitored components to be detected. A high feed voltage can stem from an overcharging alternator or DC/DC converter, a jump start from a 24 V source, or a sensing line shorted to another powered circuit. In some designs a feed that stays live after shutdown, for example because of a stuck relay, is also judged as high. The pump electronics may switch off to protect themselves, and other modules often log overvoltage codes at the same time.

Likely causes

Overcharging alternator or DC/DC converter
Supply relay stuck closed so the feed stays live
Feed or sensing wire shorted to another powered circuit

Symptoms

  • Check engine lamp on
  • Overvoltage codes in other control modules

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€20–900
Time0.3–2.5 h

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

Parts involved

smart coolant pump modulesupply circuitcharging system

Related codes

P26D3P26D4P26D1P26CD

References: law.cornell.edu, fordservicecontent.com.