HomeTrouble CodesP2063

P2063 — Reductantregeneration Supply Control Circuit Low

Manufacturer-specificPowertrain (engine & transmission)

P2063 indicates a low voltage condition in the electrical circuit controlling the diesel exhaust fluid injection system. This fault prevents the engine management system from properly dosing reductant into the exhaust stream for emissions control. The issue is typically electrical rather than mechanical or fluid-related.

Symptoms

What causes it — most likely first

1. Damaged wiring harness near exhaust components

Heat and vibration often cause insulation breakdown or shorts in the undercarriage wiring.

2. Corroded electrical connector at the injector

Exposure to road salts and moisture leads to high resistance at the connection point.

3. Failed reductant injection valve assembly

Internal electrical failure within the valve creates an open or low resistance circuit.

4. Blown fuse in the reductant supply circuit

A power protection device may have opened due to a momentary surge or short.

5. Malfunctioning DEF control module

The dedicated controller for the SCR system may have internal circuit board failure.

6. Rare PCM internal circuit driver failure

Main engine computer failure is possible but statistically unlikely compared to wiring or components.

How it's diagnosed

  1. Retrieve all stored codes and freeze frame data
  2. Visually inspect wiring for heat damage or chafing
  3. Check all relevant fuses and relays for continuity
  4. Measure voltage and resistance at the injector connector
  5. Test circuit continuity between injector and controller
  6. Verify power and ground at the control module

Code facts & related codes

SystemPowertrain (engine & transmission)
StandardizationManufacturer-specific (P1/B1/C1/U1)

Frequently asked

Is replacing the PCM the fix for P2063?

No, PCM failure is extremely rare; wiring and the injector valve are the primary suspects.

Can I continue driving with this code?

Short trips are possible, but the vehicle may enter limp mode or refuse to restart eventually.

Does this mean I am out of DEF fluid?

No, this is an electrical circuit fault, not a low fluid level warning.

Will disconnecting the battery clear this code?

No, the fault will return immediately once the monitor runs if the electrical issue persists.