P2063 — Reductant/Regeneration Supply Control Circuit Low #

Note: The code label may vary depending on the vehicle manufacturer.

• Reductant Supply Control Circuit Low (General/SAE)
• SCR Urea Pump Supply Control Circuit Low (GM, Ford, Chrysler)
• AdBlue Pump Control Circuit Low (Mercedes-Benz, BMW, Volkswagen)
• DEF Dosing Pump Control Circuit Low (Cummins, Caterpillar)

Summary of code P2063 #

P2063 is a generic OBD-II diagnostic trouble code (DTC) that indicates the engine control module (ECM) has detected a low voltage condition in the reductant supply control circuit. In most modern diesel vehicles, this circuit controls the reductant (DEF/AdBlue/urea) pump responsible for delivering the urea-based fluid into the Selective Catalytic Reduction (SCR) system. The SCR system helps convert harmful nitrogen oxide (NOx) emissions into harmless nitrogen and water. When this circuit’s voltage is lower than expected, the proper operation of the emission system is at risk. The ECM triggers this code to alert the driver or technician to potential issues that could affect both performance and emissions compliance.

Frequent symptoms for code P2063 #

When the P2063 code is present, your vehicle may exhibit several warning signs—some obvious, others subtle. Typically, the check engine light will illuminate. You might also notice a change in engine performance or emission warnings. Here are the most common symptoms:

• Illuminated Check Engine Light (CEL)
• DEF/AdBlue warning light or message displayed on the dashboard
• Reduced engine power (limp mode) in some vehicles
• Increased NOx emissions (may cause failed emissions test)
• Possible starting restrictions after repeated driving cycles

Most probable causes for code P2063 #

Several possible issues can trigger a P2063 code, but some are more common than others. The causes range from simple electrical faults to component failures. In order of likelihood, the most frequent causes include:

1. Faulty reductant (DEF/AdBlue) supply pump — mechanical or electrical failure
2. Wiring problems — damaged, corroded, or shorted wires/connectors in the pump control circuit
3. Defective reductant supply relay or fuse
4. Low DEF/AdBlue fluid (rarely, but low fluid can sometimes cause system errors)
5. Defective Engine Control Module (ECM/PCM) (rare)

Step-by-step diagnostic for code P2063 #

A methodical approach is essential for accurately diagnosing the root cause of P2063. Here’s a proven diagnostic procedure you can follow:

1. Verify the code — Use an OBD-II scanner to confirm P2063 is active. Clear the code and see if it returns.
2. Inspect the DEF/AdBlue fluid level — Ensure the tank is filled with the correct fluid.
3. Visually inspect the DEF supply pump and wiring — Check for damaged, disconnected, or corroded connectors and wires.
4. Test the supply pump circuit — Using a multimeter, check for proper voltage at the pump connector with the ignition on.
5. Check relevant fuses and relays — Replace any blown fuses or faulty relays controlling the DEF pump circuit.
6. Test the pump itself — If possible, bench-test the pump for internal faults or excessive resistance.
7. Check for related codes — Codes like P20E8, P20B9, or P20C9 can provide more context.
8. Consult OEM wiring diagrams — Trace the circuit if all else fails, and check the ECM’s output signal.

Possible repairs for code P2063 #

The right repair depends on the cause found during diagnosis. Here are the most common fixes associated with P2063:

• Replace the defective DEF/AdBlue supply pump
• Repair or replace damaged wiring or connectors in the pump circuit
• Replace a faulty relay or blown fuse for the DEF supply circuit
• Refill the DEF/AdBlue tank with the correct fluid if low
• Replace the ECM/PCM (rare; only after all other causes are ruled out and confirmed by OEM diagnostics)

Can you drive with code P2063? #

Limited — While your vehicle will usually remain drivable with code P2063, it’s strongly recommended to address the issue as soon as possible. Some vehicles will enter limp mode (reduced power) or may eventually prevent the engine from starting if the issue is not resolved. Continued operation with a malfunctioning SCR system can lead to failed emissions tests, increased pollution, and, in some regions, legal restrictions. Act promptly to avoid costly repairs or breakdowns.

Most commonly affected vehicles by code P2063 #

P2063 is most often seen on modern diesel vehicles equipped with SCR and DEF/AdBlue systems. The following brands and models are frequently affected:

• Ford Super Duty (F-250, F-350) and Transit (with Power Stroke Diesel)
• Chevrolet Silverado/GMC Sierra (Duramax Diesel)
• Dodge Ram Cummins Diesel
• Mercedes-Benz Sprinter and Bluetec models
• BMW diesel models (328d, X5 xDrive35d)
• Volkswagen TDI models
• Freightliner and other heavy-duty trucks with SCR/DEF systems

Common mistakes and best practices for code P2063 #

Misdiagnosing P2063 can lead to unnecessary and expensive repairs. Here’s what to avoid, and some expert tips:

• Replacing the DEF pump without checking wiring or fuses first
• Ignoring corroded or damaged connectors — electrical issues are common causes
• Overlooking fluid contamination — always use quality DEF/AdBlue fluid
• Not consulting OEM diagrams or service bulletins
• Failing to clear codes and retest after repairs

Express FAQ for code P2063 #

Here are quick answers to the most common questions about P2063:

• Q: Can a bad DEF pump cause other codes?
• A: Yes, a failing pump can trigger related codes (e.g., P20E8, P20B9) due to low pressure or flow in the SCR system.
• Q: Will clearing the code fix the problem?
• A: No. Clearing the code will turn off the warning temporarily, but the underlying issue must be repaired for a permanent fix.