P2064: Reductant/Regeneration Supply Control Circuit High

P2064 closes the supply control group that begins with P2062. The line that switches power to the reductant supply, in a few layouts to regeneration hardware, carries a level that only a connection to a positive feed can explain, or the stage stays live while the controller has it switched off. No manufacturer documents P2064 publicly. Related component codes show how such a fault is caught: Deutz files a DEF pump high side shorted to battery as P05F0-00 on its EMR L1 secondary controller, and Ford's 2023 diesels set P208D once pump voltage tops 16 V or the pump controller draws over 5 A with the driver on, confirmed within 2 s. Suspects are a chafed wire touching a powered circuit, a welded relay contact or a wet connector. Unlike P2063 the pump may keep running unbidden, yet dosing is still suspended.

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

MIL and SCR or DEF warning in the cluster
DEF pump audible after it should have stopped
Countdown toward speed limit or no-restart after repeated faults

Most likely causes

Control line chafed through and touching a powered wire
Supply relay contact welded closed
Water or corrosion bridging pins in the supply connector
Faulty output stage in the controlling module

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
Check the sensor's ground and make sure the signal wire is not receiving voltage from another circuit.
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 P2064 means

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

Frequently asked questions

Can I keep driving with code P2064?

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

What causes code P2064?

The most common causes are: control line chafed through and touching a powered wire; supply relay contact welded closed; water or corrosion bridging pins in the supply connector.

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.