P2063: Reductant/Regeneration Supply Control Circuit Low

P2063 says the reductant or regeneration supply control circuit reads too low, the classic signature of a grounded control line or of a load drawing far more current than it should, which pulls the driver output down. No manufacturer documents P2063 publicly. The comparable component code in Ford's 2023 diesel summary is P208C, set when reductant pump current exceeds 5 A or the pump controller draws more than 15 A; Deutz files a grounded DEF pump high side as P05EF-00. Seized pump motors, especially after DEF has crystallised, and harness damage near the tank are the usual suspects. While P2062 means no current at all, here the stage is overloaded, and fuses or relays may be found burnt. Dosing is suspended until the circuit is repaired.

Medium severity. Can I keep driving?Deal with it soon. If the instrument cluster shows a countdown, the car may not restart once it reaches zero.

Symptoms

Engine or emission warning lamp on
Fuse for the DEF supply blows repeatedly
Dosing suspended, possible speed or restart limitation

Most likely causes

Supply control wire shorted to ground near the tank
Pump motor seized or blocked by DEF crystals
Internal short in the pump winding

What to check, in order

Start with the simplest. You can tick off each step.

Check the AdBlue/DEF level and quality, and do not add additives or water
With the connector unplugged, check whether the signal wire is making contact with ground.
Look for white crystals around the injector and the tank
Check connectors and heaters with the scanner
Run the dosing test available on your diagnostic tool
Replace parts only when the test points to that component

Good to know

Repair difficulty: medium
It can trigger limp mode.
It affects emissions.

What each character of P2063 means

P: Powertrain: engine and transmission
2: Generic code: same on every make
0: Subsystem depends on the code range
63: Specific fault in that system

Frequently asked questions

Can I keep driving with code P2063?

Deal with it soon. If the instrument cluster shows a countdown, the car may not restart once it reaches zero.

What causes code P2063?

The most common causes are: supply control wire shorted to ground near the tank; pump motor seized or blocked by DEF crystals; internal short in the pump winding.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.