Powertrain, generic

P0E21 Hybrid/EV Battery Pack Coolant Control Valve B Control Circuit Driver Current/Temperature Too High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0E21 is the overload or overheat report of the driver for coolant control valve B. No manufacturer documents P0E21 publicly. What B means differs between makers: on the 2011 Chevrolet Volt, GM's own codes for valve B (P1EC7, P1EC8) actually watch the second drive line of the same valve motor that serves as valve A, whereas other layouts have a physically separate second valve for a chiller or radiator branch. For diagnosis it is therefore worth checking first which actuator the maker calls B. The protection itself works like that of TI's integrated high-side switches for cars, which cut off at their current limit or near 150 °C and report it. CARB obliges makers to monitor these outputs electrically. Electrical circuit faults of valve B are P0D1A, P0D1D and P0D1E.

Likely causes

Valve B binding so its actuator stalls against the stop
Short or low resistance in the valve B actuator or harness
Degraded driver stage in the control module

Symptoms

  • Check engine light on
  • Coolant routing does not change as commanded
  • Battery temperature drifts, power or charging limited

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€100–900
Time0.5–3 h

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

Parts involved

hv battery pack coolant valve bbms

Related codes

P0E20P0E22P0D1AP0D1DP0D1EU0637

References: gsi.ext.gm.com, ti.com, law.cornell.edu.