Powertrain, generic (extended)

P2B28 Hybrid/EV Battery Pack Coolant Pump A Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

P2B28 means battery coolant pump A is electrically reachable but does not perform as the battery controller expects. VW and Audi store P2B2800 in battery management J840: VW bulletin 93-21-02 (2021 ID.4) traces it to air left when pump V590 did not run during the fill-and-bleed routine, and Audi's 2068363 series (Q4 e-tron 2022–2024, message Electric drive fault) names dry running from residual air, prescribes two bleed runs with the battery at 3–35 °C and replaces V590 only if the entry stays static. FCA lists P2B28 with MIL on the Jeep Wrangler eTorque mild hybrids (2.0 L, 3.6 L) and reflashes the battery pack module or hybrid control processor. Thresholds are not published. The dry-run code is P2B29, a stalled pump P0CFF.

Likely causes

Residual air in the battery coolant loop, often after service
Battery or hybrid controller software needing an update
Worn or failing battery coolant pump
Low coolant level from a leak

Symptoms

  • Electric drive fault message or MIL
  • Reduced drive or charging power
  • Short or missing engine auto-stops on mild hybrids

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–900
Time0.3–3 h

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

Parts involved

hybrid battery coolant pump abattery packhybrid control module

Related codes

P2B29P0CFFP0C4AP0C47P0E3B

References: static.nhtsa.gov, static.nhtsa.gov, static.nhtsa.gov, static.nhtsa.gov.