Powertrain, generic (extended)

P26A3 Engine Coolant Bypass Valve A Range/Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P26A3 is a functional fault: the electrics of bypass valve A look fine, but the valve does not reach or report the position it should. GM's 2011 Volt table sets it, Type B, when the end-position learn fails with coolant above 50 °C, or when the valve has not arrived at its commanded position within 15 s. Honda calls the part an electric water valve: on the 2014 Accord Plug-In Hybrid, bulletin 20-033 blames climate control software that drove the three-way valve wrongly and replaces that unit; on the 2018 Clarity Plug-In Hybrid, 18-090 is an emissions recall with new engine software. Ram 1500 3.6 L trucks show it after a cracked valve gear or, per 07-007-24, contamination by stop-leak pellets requiring a flush.

Likely causes

Broken gear or jammed rotor inside the bypass valve
Contaminated coolant, e.g. stop-leak additives, blocking the valve
Engine or climate control software commanding the valve incorrectly
End-position learn not completed after replacement

Symptoms

  • Check engine light on
  • Weak or delayed cabin heat
  • Unusual coolant or transmission temperatures

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€0–800
Time0.3–3 h

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

Parts involved

coolant bypass valve athermostat housing

Related codes

P2681P26A9P26A6P26ABP26B1P26B0

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