Powertrain, generic (extended)

P26AE Engine Coolant Bypass Valve B Control Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

With P26AE the valve B drive output sees voltage where it expects none, typically a short to battery. GM's 2016 Volt table again applies it to the second drive line of the one bypass valve: the VICM sets it when driver 2 flags a short to high while the valve is stopped or commanded low, after 16 failures in 20 samples at 100 ms, Type B. Ford's 2024–2025 gasoline summary lists P26AE as the short-to-battery case of the active transmission cooling valve, also filed as P26AC_12, detected when the smart driver reports a fault for 5 s. A pinched harness touching a supply wire or an internally shorted valve motor are the main causes; drivers often protect themselves by switching off, so the valve stops moving.

Likely causes

Drive wire shorted to a battery-voltage wire
Internally shorted valve motor or solenoid drawing excess current
Damaged output stage in the control module

Symptoms

  • Check engine light
  • Valve stays in its last position
  • Transmission or cabin temperature control off target

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–700
Time0.5–2.5 h

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

Parts involved

coolant bypass valve bsolenoidwiring harness

Related codes

P26ADP26ACP2683P26A9

References: gsi.ext.gm.com, fordservicecontent.com.