What it means
The reductant/regeneration supply control circuit voltage is lower than expected. The code identifies a low circuit condition; the specific cause depends on the vehicle.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The reductant/regeneration supply control circuit operates a vehicle-specific DEF supply or regeneration component. The control module monitors the circuit voltage when that component is commanded. P2063 sets when voltage is below the expected level, which can prevent the component from working correctly.
Common causes
Most likely first.
- Short to ground
- Connector pins corroded - high contact resistance
- Harness chafing through insulation
Symptoms
- Check engine light or NOx warning on
- AdBlue/DEF level or quality warning
- Possible no-start countdown after ignore period
- Failed emissions inspection (NOx)
How to diagnose it
- Save freeze-frame data and check for related reductant supply or regeneration codes to determine when the low voltage occurred.
- Use the vehicle's wiring diagram to identify the affected circuit and component before inspecting it.
- Inspect the connector and harness for corrosion, moisture, loose terminals or insulation worn through to ground.
- Check terminal fit and test the control circuit for a short to ground or excessive resistance, following the manufacturer's procedure.
- If wiring and connections pass, test the affected pump, heater or control device as specified by the manufacturer.
Common fixes
- Clean and secure corroded or loose circuit terminals.
- Repair chafed wiring that is contacting ground.
- Replace a damaged connector or harness section.
- Replace the affected supply or regeneration component if testing confirms an internal fault.
Can I keep driving?
The vehicle may run normally, but DEF supply or regeneration may be affected and emissions can rise. Have the circuit checked promptly, especially if an SCR warning or no-start countdown appears.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.