A blown fuse or tripped circuit breaker supplying power to the reductant pump; An open or damaged wire in the supply voltage circuit between the fuse box and the reductant pump; Corroded, loose, or disconnected electrical connector at the reductant pump or inline harness; A failed reductant pump with an internal open circuit in its supply voltage feed; A faulty reductant pump control module or relay that fails to deliver voltage to the pump; High resistance in the ground circuit for the reductant pump, causing a voltage drop that mimics an open supply; A damaged or chafed wiring harness caused by road debris, heat, or improper routing

DTC codes / P05xx · Vehicle speed, idle control and auxiliary inputs / P05EE

P05EEReductant Pump Supply Voltage Circuit/Open

Q: What does code P05EE mean?

Reductant Pump Supply Voltage Circuit/Open. P05EE indicates that the powertrain control module has detected an open circuit or voltage supply fault on the reductant pump supply voltage circuit, which is part of the selective catalytic reduction system used to inject diesel exhaust fluid. The computer monitors the voltage feed to the reductant pump and sets this code when the expected voltage is missing or out of range, preventing the pump from operating.

P05EE indicates that the powertrain control module has detected an open circuit or voltage supply fault on the reductant pump supply voltage circuit, which is part of the selective catalytic reduction system used to inject diesel exhaust fluid. The computer monitors the voltage feed to the reductant pump and sets this code when the expected voltage is missing or out of range, preventing the pump from operating.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaVehicle speed, idle control and auxiliary inputs

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
A message on the driver information display indicating low diesel exhaust fluid or a reductant system fault
Reduced engine power or limp mode if the fault persists and the system cannot maintain emissions compliance
Difficulty starting the engine or an engine that stalls shortly after starting in severe cases
A noticeable decrease in fuel economy as the engine management strategy compensates for the fault

Common causes, most likely first

A blown fuse or tripped circuit breaker supplying power to the reductant pump
An open or damaged wire in the supply voltage circuit between the fuse box and the reductant pump
Corroded, loose, or disconnected electrical connector at the reductant pump or inline harness
A failed reductant pump with an internal open circuit in its supply voltage feed
A faulty reductant pump control module or relay that fails to deliver voltage to the pump
High resistance in the ground circuit for the reductant pump, causing a voltage drop that mimics an open supply
A damaged or chafed wiring harness caused by road debris, heat, or improper routing

How to diagnose and fix it

Verify the battery voltage and check all fuses and relays related to the reductant pump supply circuit, replacing any that are blown or faulty
Inspect the reductant pump electrical connector and harness for corrosion, loose pins, or physical damage, cleaning or repairing as needed
Measure voltage at the reductant pump supply terminal with the key on and engine off, comparing to the manufacturer's specification to confirm the open circuit
Perform a voltage drop test on both the positive supply and ground circuits to identify high resistance points that could cause the code
Check the reductant pump control module for proper output signals and communication, using a scan tool to command the pump on and observe voltage changes
If voltage is present at the pump but the pump does not operate, test the pump motor directly with a known good power source to confirm pump failure
Repair or replace any damaged wiring, connectors, or components found during testing, then clear the code and verify the repair with a test drive

Reductant pump supply circuit pitfalls

A common oversight is assuming the reductant pump itself has failed when the actual problem is a blown fuse or a corroded connector that interrupts the supply voltage, so always verify power and ground before condemning the pump.
Some vehicles use a dedicated reductant pump control module that can set this code if its internal relay fails, and this module is often overlooked during diagnosis because it is not always located near the pump.
The code can be set intermittently by a wiring harness that rubs against the frame or exhaust component, so a wiggle test of the harness while monitoring voltage can reveal an open circuit that only appears under vibration.
A weak battery or charging system fault can cause the reductant pump supply voltage to drop below the threshold, setting P05EE even though the pump circuit itself is intact.
After repairing the circuit, some vehicles require a reductant system reset or adaptation procedure with a scan tool before the code will clear and stay cleared, otherwise it may reappear immediately.

Can I keep driving with P05EE?

You can usually drive the vehicle short distances to a repair shop, but avoid long trips or heavy loads because the engine may enter limp mode and reduce power unexpectedly. If the check engine light flashes or the engine runs poorly, stop driving and have the vehicle towed to prevent further damage.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.