OBD Reductant Heater Control Module Supply Voltage
What it means
P05ED stands for Reductant Heater Control Module Supply Voltage. P05ED is a P code, so the fault sits in the engine, transmission and emissions systems. For P05ED, the second digit places it in speed and idle control. For P05ED, work through the cause list below, cheapest checks first.
Where it lives
For P05ED, the description names the module as the part involved.
What to check first
For P05ED, read the stored codes from every module, not just the engine, because related codes often name the same fault more precisely.
Check these first
- P05ED: Faulty sensor or actuator in the control circuit
- P05ED: Wiring, connector, or fuse problem for the affected output
- P05ED: Low or unstable system voltage from the battery or charging system
- P05ED: Failed PCM/ECM or a software error
- P05ED: Poor ground connection for the control module
What to do next
P05ED is a fault in the speed and idle control system. The steps below are general, so what actually failed on your vehicle may not be what P05ED names.
- P05ED: Verify battery voltage and charging system health first
- P05ED: Read all related module codes with an OBD-II scanner
- P05ED: Inspect wiring, connectors, and grounds for the affected circuit
- P05ED: Test the sensor or actuator with live data and actuation commands
- P05ED: Check for PCM software updates or TSBs before replacing modules
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Updated
Generic SAE J2012 definition. Last updated 2026-08-30.