Powertrain, generic (extended)

P2DA4 Coolant Heater A Internal Control Module Performance

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

Coolant heater A here is an electric heater with built-in electronics, usually a high-voltage PTC or wire-element unit that warms coolant for cabin and battery in hybrids and EVs; it is separate from the engine block heater codes P01E8 ff. P2DA4 says that heater's own controller has found a fault in itself – a power switch that shorted, a temperature or current measurement that fails, or a processor error. Texas Instruments describes the usual layout: one controller on the 12 V side for LIN or CAN, one on the HV side that drives the elements and cross-checks current, voltage and temperature. No manufacturer documents P2DA4 publicly; Ford stores the sister code P2DA6 in the module SOBDMC on the F-150 Lightning. The heater is switched off, so expect little heat in electric mode.

Likely causes

Power switch inside the heater shorted or failed
Internal temperature or current measurement faulty
Coolant or moisture inside the electronics housing
Software fault in heater or commanding module, update available

Symptoms

  • Little or no cabin heat in electric mode
  • Engine of a hybrid runs more often just to supply heat
  • Climate system message, usually without check engine light

Repair estimate

DifficultyHardWorkshop job
Parts and labour€400–2,000
Time1–4 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

P2DA5P2DA6P2DA7U069EP2B75

References: ti.com, static.nhtsa.gov, law.cornell.edu.