Powertrain, generic (extended)

P26A7 Engine Coolant Bypass Valve A Position Sensor Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

The counterpart to P26A6: the feedback from valve A reads too high. GM's 2016 Volt table counts both a signal above its window and a broken signal circuit here, because an interrupted wire lets the input float toward the reference. The limit is 95 % of the reference (4.75 V), checked as 40 failures in 50 samples at 100 ms, Type B. The 2011 Volt table uses the same 95 % rule but prints the voltage as 4.25 V. Subaru's correction bulletin 09-132-25 also covers P26A7 for its boxer engines and again drops the first step of the published test. Subaru's earlier bulletin 09-80-21 replaced the thermo control valve with a better sealed sensor section. Check for a broken signal or ground wire and for a short to the 5 V supply before condemning the valve.

Likely causes

Open feedback or sensor ground wire
Feedback wire shorted to 5 V reference or battery voltage
Defective sensor in the valve housing

Symptoms

  • Check engine light
  • Scan tool shows valve position at maximum
  • Engine slow to reach operating temperature

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–800
Time0.5–3 h

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

Parts involved

coolant bypass valve aposition sensorwiring harness

Related codes

P26A6P26A4P26A5P26A8P2681

References: gsi.ext.gm.com, gsi.ext.gm.com, static.nhtsa.gov, static.nhtsa.gov.