P2B10

Reductant Pump Control Circuit Open

P2B10 is a generic OBD-II powertrain diagnostic trouble code: Reductant Pump Control Circuit Open. 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
P2B10
Group
Powertrain
System
Powertrain
Severity
Warning (MIL on, possible limp mode)
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What P2B10 means

P2B10 is set when the PCM or SCR control module detects an open circuit condition in the control circuit for the reductant (DEF/AdBlue) pump. The reductant pump is responsible for pressurizing the DEF supply line to deliver urea solution to the SCR dosing injector. An open control circuit means the module cannot command the pump to operate, effectively disabling DEF delivery and rendering the SCR system non-functional.

The control circuit typically carries a PWM or switched ground signal from the module to the pump driver. An open in this circuit can occur due to a broken wire, a failed pump motor winding, a disconnected connector, or a fault within the module's output driver. Some systems use a relay in the pump circuit, and a failed relay or open relay control circuit can also produce this code.

When DEF delivery is disabled, the SCR catalyst cannot convert NOx, and on vehicles with regulatory derate strategies, the engine may enter a progressive torque reduction after a set number of fault drive cycles. Prompt diagnosis and repair is important to avoid derate escalation and to restore emissions compliance. The fault must be repaired and a successful DEF delivery cycle confirmed before the module will exit its default strategy.

Common causes

Most-frequently reported root causes when P2B10 is logged.

  • 1
    Open circuit in the reductant pump control wiring.
  • 2
    Disconnected or damaged reductant pump electrical connector.
  • 3
    Failed reductant pump motor winding (open internal circuit).
  • 4
    Blown fuse in the pump supply circuit.
  • 5
    Failed relay controlling pump power (if relay-operated system).
  • 6
    Open circuit in the module-side output driver for the pump.
  • 7
    Corroded or pushed-back terminal in the pump harness connector.

Symptoms drivers notice

MIL illuminated with possible DEF system warning light.
DEF pump not audible during ignition-on prime cycle.
No DEF flow; SCR system unable to dose reductant.
Progressive engine torque derate on vehicles with regulatory compliance strategies.
Possible secondary NOx sensor codes due to absence of DEF.

How to diagnose P2B10

A typical diagnostic flow when this code is present.

  1. 1
    Read all DTCs and freeze frame data; note any accompanying SCR or NOx codes.
  2. 2
    Check for power and ground at the reductant pump connector with the ignition on.
  3. 3
    Inspect the pump control wire for opens and the connector for damaged or corroded terminals.
  4. 4
    Check the pump fuse and relay (if equipped) for continuity and correct operation.
  5. 5
    Command the pump on using a scan tool bi-directional control function while monitoring circuit voltage.
  6. 6
    Measure pump motor resistance to identify an open winding if power and control circuits are intact.
  7. 7
    Repair wiring or replace the pump as indicated; confirm pump operation with a scan tool activation test.

Related powertrain codes

Frequently asked questions

Will this code cause my engine to derate?

On commercial and passenger diesel vehicles subject to emissions derate strategies, yes. If the SCR system cannot dose DEF, a progressive power reduction may be imposed after multiple fault drive cycles.

Can I hear when the pump is not working?

On most vehicles the DEF pump primes briefly after ignition-on. If you no longer hear this priming sound, the pump may not be receiving power or may have failed mechanically.

Is P2B10 the same as a pump failure?

Not necessarily. An open control circuit means the electrical path to the pump is broken, which could be a wiring fault, fuse, or relay issue rather than a pump failure.

How do I confirm the pump is the fault rather than the wiring?

If power supply and control circuit wiring check out correctly at the pump connector, measure pump motor resistance. An open reading confirms an internal pump winding failure.

Disabling P2B10 in software

RaceTune can permanently disable P2B10 — 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 P2B10 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 EDC16C31 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.

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