Reductant/Regeneration Supply Control Circuit Low
What it means
P2063 means the engine computer detected low voltage on the control circuit that drives the reductant (DEF/AdBlue) supply or regeneration system. That circuit controls the pump or valve delivering fluid for exhaust after-treatment. The engine keeps running, but with the supply control faulted the emissions system can't dose correctly, and many diesels will derate power or restrict restarts until it's repaired.
Can I keep driving? Yes short term, but this is a diesel emissions supply-control fault — expect derated power or restart limits if the DEF/regeneration system stays down. Repair promptly.
Common symptoms
What you'll notice
- Check-engine light on
- SCR/DEF or emissions warning messages
- Usually no immediate change in drivability
- Reduced power (derate) or restart limits if left unrepaired
Common causes
Most likely first
- Low voltage (short to ground or open) in the reductant/regeneration supply control circuitLikely
- Faulty reductant supply/metering pump or control unitCommon
- Damaged or corroded wiring and connectors in the supply control circuitCommon
- Poor ground or electrical connectionLess often
- Faulty powertrain control module (PCM)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and confirm the fault is on the reductant/regeneration supply control circuit.
- Inspect the control wiring and connectors for a short to ground, opens, or corrosion; repair as needed.
- Check the reductant supply/metering pump's power, ground, and control signal against spec.
- Replace the supply control component (pump/valve) if it fails testing.
- Clear the code and re-run the drive cycle; if it persists with good wiring, test the PCM.
FAQ
Quick answers
Is it safe to drive with P2063?+
Can I just clear P2063?+
Related codes
Often seen with P2063
Read & clear P2063 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.