P263A

Reductant Pump Motor Current Low

P263A is a generic OBD-II powertrain diagnostic trouble code: Reductant Pump Motor Current Low. It is logged by the engine control unit when the powertrain monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
P263A
Group
Powertrain
System
Powertrain
Severity
Warning (MIL on, possible limp mode)
Need P263A disabled?
RaceTune permanently disables any OBD-II trouble code on supported ECUs — for motorsport, off-road, and export use.
→

What P263A means

P263A is set when the ECM measures a lower-than-expected current draw from the SCR reductant (DEF/AdBlue) pump motor. The ECM monitors motor current as a proxy for pump load and operation; a current reading below the calibrated minimum while the motor is commanded on indicates that the motor is not drawing the expected power, suggesting it is not running or is running without load.

Low motor current can result from an open circuit preventing current flow to the motor, a failed motor winding with high internal resistance, or a shorted feedback sense resistor in the control circuit. It may also be triggered if the DEF tank is empty and the pump is running dry with no hydraulic load. Unlike P261B which indicates a high-current fault, P263A points to a motor that is consuming less current than anticipated.

The SCR system cannot function without a working pump, so the ECM will typically disable dosing and may initiate a derate after extended operation. Diagnosis should begin with verifying DEF fluid level, then proceed to electrical testing of the motor and its supply circuit.

Common causes

Most-frequently reported root causes when P263A is logged.

  • 1
    Open circuit in the pump motor supply or ground wiring.
  • 2
    Empty DEF tank causing the pump to run dry with no hydraulic load.
  • 3
    Failed reductant pump motor winding with high resistance.
  • 4
    Blown fuse in the pump motor power circuit.
  • 5
    Corroded or loose connector pins at the DEF pump module.
  • 6
    Faulty current-sense feedback circuit within the pump control module.
  • 7
    Frozen DEF lines or pump preventing motor from drawing load current.

Symptoms drivers notice

MIL and diesel exhaust fluid (DEF) warning lamp illuminated.
SCR dosing inactive, increasing NOx emissions.
Vehicle derate (torque or speed reduction) after fault confirmation period.
DEF pump inaudible during cold start priming cycle.
Scan tool shows zero or near-zero reductant pump current in live data.

How to diagnose P263A

A typical diagnostic flow when this code is present.

  1. 1
    Connect a scan tool and record all SCR-related codes and freeze-frame data.
  2. 2
    Verify DEF fluid level; refill if low or empty and retest.
  3. 3
    Check the DEF pump fuse and any associated relay for continuity.
  4. 4
    Measure supply voltage and ground at the pump motor connector while commanding the pump on via scan tool.
  5. 5
    Measure motor winding resistance and compare to manufacturer specifications; high resistance indicates motor failure.
  6. 6
    Inspect the harness for open circuits or corroded pins between the ECM and the pump module.
  7. 7
    Replace the reductant pump module if wiring and fuse checks are satisfactory and motor resistance is out of specification.

Related powertrain codes

Frequently asked questions

Can an empty DEF tank set P263A?

Yes. With no fluid present the pump has no hydraulic load and may draw less current than the ECM expects, potentially triggering a low-current fault alongside the low-level warning.

Is P263A the same as a DEF pump failure?

It indicates a low-current condition that is consistent with pump motor failure, but an open circuit in the wiring can produce the same result without the pump itself being faulty.

How long does the SCR derate warning period last?

The derate activation window varies by manufacturer and jurisdiction but is often in the range of several hundred miles after the fault is first confirmed.

Will adding DEF clear P263A?

Only if the root cause was a dry-running pump. If there is an electrical fault, adding DEF will not clear the code.

Disabling P263A in software

RaceTune can permanently disable P263A — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

ECUs with a P263A disable in our catalogue

Confirmed coverage from our recipe database — we support many more families. Upload your file and our identifier will match it automatically.

  • Bosch MD1CS001 verified 1 software version

Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.

Got P263A in your scan?

Upload your ECU file — we'll identify the exact software version and confirm whether a disable is available for your car.

Upload your file