Damaged or corroded wiring harness to the reductant pump; Faulty reductant pump A (internal short or open); Poor electrical connection at the pump or control module; Blown fuse or relay supplying power to the pump circuit; Failed pump control module or driver in the powertrain control module; Contamination or debris in the diesel exhaust fluid tank causing pump damage

DTC codes / P20xx · Fuel and air metering and auxiliary emission controls / P208C

P208CReductant Pump A Control Circuit Low

Q: What does code P208C mean?

Reductant Pump A Control Circuit Low. P208C indicates that the powertrain control module has detected a low voltage condition on the control circuit for reductant pump A, which is part of the diesel exhaust fluid system. The computer expects a certain voltage range when commanding the pump, but the actual signal is below the threshold, suggesting a short to ground, an open circuit, or a faulty pump.

P208C indicates that the powertrain control module has detected a low voltage condition on the control circuit for reductant pump A, which is part of the diesel exhaust fluid system. The computer expects a certain voltage range when commanding the pump, but the actual signal is below the threshold, suggesting a short to ground, an open circuit, or a faulty pump.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering and auxiliary emission controls

Symptoms you may notice

Illumination of the check engine light, often with no other symptoms
Reduced engine power or limp mode
Diesel exhaust fluid warning message on the dashboard
Increased diesel exhaust fluid consumption or failure to dose
Rough running or poor fuel economy in some cases
No noticeable change in vehicle behavior besides the warning light

Common causes, most likely first

Damaged or corroded wiring harness to the reductant pump
Faulty reductant pump A (internal short or open)
Poor electrical connection at the pump or control module
Blown fuse or relay supplying power to the pump circuit
Failed pump control module or driver in the powertrain control module
Contamination or debris in the diesel exhaust fluid tank causing pump damage

How to diagnose and fix it

Inspect the reductant pump wiring and connectors for damage, corrosion, or loose pins
Check the fuse and relay related to the reductant pump circuit
Measure resistance and voltage on the control circuit to identify a short or open
Test the reductant pump with a scan tool bidirectional control to verify operation
Replace the reductant pump if electrical tests indicate an internal fault
Repair or replace damaged wiring harness sections as needed
Clear the code and perform a road test to confirm the repair

Before replacing the reductant pump

A low voltage code often results from a poor ground connection rather than a failed pump, so always check grounds first.
Diesel exhaust fluid crystallization can cause pump damage and set this code, especially in cold climates or with old fluid.
The control circuit may be shared with other sensors, so a fault elsewhere can trigger P208C without the pump being defective.
After repairs, the system may require a relearn or adaptation reset with a scan tool to clear the code permanently.
Some vehicles will not allow the engine to start if the reductant pump circuit is faulty, so address the issue promptly.

Can I keep driving with P208C?

It is generally safe to drive with P208C, but the vehicle may enter limp mode or fail to start if the fault worsens. Avoid long trips and have the system diagnosed soon to prevent further damage.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

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