Powertrain, generic (extended)

P2DA5 Coolant Heater A Supply Voltage Circuit

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

P2DA5 concerns the feed that powers coolant heater A, the electric coolant heater with its own electronics found in hybrids and EVs. The heater's controller finds its supply input missing or outside the expected window and reports it as a circuit fault, unlike P2DA7, which rates the voltage level of the module. Which feed is meant is up to the maker. Texas Instruments shows that such heater modules run their logic from the 12 V rail and can watch that rail for leaving its operating range, while the heating elements draw from the HV battery. No manufacturer documents P2DA5 publicly. Typical findings are a blown fuse, a corroded pin in the low-voltage connector, a poor ground or an open HV fuse in the distribution box. The heater stays off until the feed is restored.

Likely causes

12 V or HV fuse for the heater open
Corroded or loose pin in the heater supply connector
Poor ground connection of the heater electronics
Supply input inside the heater electronics faulty

Symptoms

  • No heat from the electric coolant heater
  • Cabin heat only when the engine of a hybrid runs
  • Possibly lost communication with the heater stored at the same time

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€30–1,800
Time0.5–4 h

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

Parts involved

coolant heater acoolant heater a control module

Related codes

P2DA4P2DA7U069EP2B72

References: ti.com, law.cornell.edu.