Powertrain, generic (extended)

P26D1 Engine Coolant Pump Control Module System Voltage High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P26D1 is stored when the electronics of the engine coolant pump report a supply voltage clearly above the vehicle system voltage. Ford documents the check in its OBD summaries for hybrid and plug-in models: the pump module passes its measured electronics voltage on via the LIN link, and a reading more than about four volts above the battery voltage seen by the PCM for five seconds sets P26D1. The 2014 Boss 302S code list from Ford Performance also carries the code. A real overvoltage comes from a failing voltage regulator or a jump start with too high a voltage; more often the pump's own measurement drifts or the PCM reference is pulled low by a bad ground, so both sides need checking. The electronics may protect themselves by switching the pump off.

Likely causes

Faulty voltage regulator or overvoltage from jump starting
Poor PCM ground making the reference voltage look low
Voltage measurement drift inside the pump electronics

Symptoms

  • Check engine lamp on
  • Unusually bright lights or other overvoltage codes

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€30–1,000
Time0.5–3 h

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

Parts involved

smart coolant pump modulecharging system

Related codes

P26CFP26D0P26D5P0563

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