P2064 — Reductant/Regeneration Supply Control Circuit High #

Note: The description of P2064 may vary depending on the vehicle manufacturer. Always refer to your OEM (Original Equipment Manufacturer) service documentation for the most accurate information.

• P2064 — Reductant Supply Control Circuit High (General)
• P2064 — Reductant Pump Control Circuit High (Ford, GM)
• P2064 — SCR Injector Supply Control High (Mercedes-Benz, BMW)
• P2064 — DEF Supply Pump Circuit High (Toyota, FCA)

Summary of the P2064 Code #

P2064 is a diagnostic trouble code (DTC) related to the reductant supply system in vehicles equipped with diesel engines and selective catalytic reduction (SCR) emissions technology. This code indicates that the Engine Control Module (ECM) has detected an abnormally high voltage or current in the circuit controlling the reductant supply mechanism—most often the DEF (Diesel Exhaust Fluid) pump or injector. This system is tasked with injecting a urea-based fluid into the exhaust stream to reduce NOx emissions. When this circuit displays higher-than-expected values, it can point to electrical faults or issues with component operation. The code often triggers the Malfunction Indicator Lamp (MIL) and may restrict engine power or emissions system function.

Frequent Symptoms for the P2064 Code #

A vehicle displaying code P2064 may exhibit a range of symptoms, from subtle performance drops to more obvious warning lights. Drivers should pay special attention to any changes in how the vehicle runs, as continued operation with this code can impact emissions compliance and, over time, engine health.

• Illuminated Check Engine Light or Service Emissions System message
• Reduced engine power or limp mode
• Unusual noises from the DEF pump area
• Noticeable drop in fuel efficiency
• Frequent regeneration cycles or failed regen attempts
• Potential for increased NOx emissions (may fail emissions testing)

Probable Causes for the P2064 Code #

The P2064 code is most often triggered by electrical issues, but mechanical failures and contamination are not unheard of. Causes are listed here in order of likelihood, but always confirm with proper diagnosis before replacing parts.

1. Short to voltage in the reductant supply circuit (wiring harness damage, corrosion, or chafing)
2. Faulty reductant pump (internal electrical short or failure)
3. Defective reductant injector (if equipped, causing excessive draw)
4. Connector issues (loose, corroded, or water-intruded terminals)
5. PCM/ECM malfunction (rare; possible internal driver fault)
6. Incorrect or contaminated DEF fluid (causing pump strain or false readings)

Step-by-Step Diagnosis for P2064 #

Diagnosing P2064 requires methodical checking of both electrical and mechanical aspects of the reductant supply system. Always consult the official OEM wiring diagrams and procedures for your specific model. Here’s a practical step-by-step process:

• Verify the code and check for other related DTCs (especially those for SCR, DEF, or NOx sensors).
• Visually inspect wiring and connectors at the DEF pump and injector for damage, corrosion, or loose connections.
• Measure supply voltage and ground at the pump/injector connector with the key ON (engine OFF), comparing against OEM specs.
• Use a digital multimeter to check circuit resistance and look for shorts to voltage or ground.
• If accessible, perform an actuator test via scan tool to command the pump/injector and monitor response.
• Check the integrity of the DEF fluid (clarity, contamination, correct type).
• If no wiring or component faults are found, recheck with a known-good PCM/ECM if possible.

Possible Repairs for the P2064 Code #

Once the root cause of P2064 is identified, repairs should address both the symptom and underlying fault. Be sure to clear the code and road test the vehicle after repairs to ensure the issue is resolved.

• Repair or replace damaged wiring harnesses (repair insulation, reconnect, or splice as needed)
• Replace faulty reductant/DEF pump if internal failure or short is found
• Replace defective reductant injector if it draws excessive current or is shorted
• Clean or replace corroded or damaged connectors
• Drain and refill with correct, uncontaminated DEF fluid if contamination is found
• In rare cases, replace or reprogram the PCM/ECM if it is determined to be at fault

Is It Safe to Drive with Code P2064? #

Driving with code P2064 is NOT recommended for extended periods. While the vehicle may continue to operate, emissions controls could be compromised, leading to higher pollution and potential regulatory noncompliance. Many vehicles will enter a reduced power or limp mode to protect the system, which can limit acceleration and speed. Immediate attention is advised to avoid further damage or failed emissions testing.

Vehicles Most Commonly Affected by P2064 #

P2064 is most often seen on modern diesel vehicles equipped with SCR/DEF systems. While the underlying technology is similar, certain makes and models report this code more frequently due to design, usage patterns, or environmental conditions.

• Ford Super Duty (F-250, F-350) with PowerStroke diesel
• Chevrolet Silverado/GMC Sierra (Duramax diesel)
• Mercedes-Benz Sprinter (BlueTEC diesel)
• Ram 2500/3500 (Cummins diesel)
• BMW X5/X3/X7 diesel models
• Toyota Land Cruiser, Hilux (diesel markets)

Common Mistakes & Best Practices for P2064 #

Misdiagnosing P2064 can lead to unnecessary parts replacement and wasted time. Following best practices can save headaches and money.

• Assuming the DEF pump is faulty without first checking for wiring or connector issues
• Failing to test the circuit with a multimeter before replacing components
• Overlooking DEF fluid quality; contaminated fluid can cause system strain
• Ignoring manufacturer-specific diagnostic steps and defaulting to generic procedures
• Not clearing codes and verifying repair effectiveness after completing work

Express FAQ for P2064 #

Q: Can a bad DEF pump cause my truck to go into limp mode?
A: Yes, a failed DEF pump can trigger P2064 and force the engine into reduced power (limp) mode to prevent excessive NOx emissions and protect the SCR system.

Q: Is it expensive to fix code P2064?
A: Costs can vary; simple wiring repairs are affordable, but DEF pump or injector replacement can be expensive, especially on OEM parts. Accurate diagnosis is key to avoiding unnecessary expenses.