P2B72Coolant Heater A Control Circuit/Open
- Generic OBD-II code · Powertrain
- How the car detects it
- P2B72 says the command line to coolant heater A is open or has lost continuity. Keep it apart from the engine coolant heater family P01E8–P01EF: the other J2012 codes for this heater – internal module, supply voltage and over-temperature under P2DA4–P2DA7, lost communication under U069E – point to a unit with its own electronics, such as the electric coolant heater of hybrids and EVs. GM's 2013–2014 Volt used a separate coolant heater control module for this job (bulletin PIC5943, no cabin heat in electric mode). No manufacturer documents P2B72 publicly, so limits and timing are unknown. CARB 13 CCR 1968.2 requires circuit monitoring of commanded outputs. In winter the cabin stays cold, or an engine runs more often to supply heat.
- What you may notice
- Little or no cabin heat, especially in electric driving
- Engine starts more often in cold weather to provide heat (hybrids)
- Warning or fault message, depending on the manufacturer
- Likely causes
- LikelyCommand wire to the heater broken or connector not latched
- PossibleTerminal pushed back or corroded in the heater connector
- PossibleInput stage of the heater electronics open internally
- RareOutput stage in the commanding control module faulty
- Repair
- Medium · Usually a job for a workshop.Typical cost: €80 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.