P208B

Reductant Pump Control Circuit Range/Performance

P208B is a generic OBD-II powertrain diagnostic trouble code: Reductant Pump Control Circuit Range/Performance. 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
P208B
Group
Powertrain
System
Powertrain
Severity
Warning (MIL on, possible limp mode)
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What P208B means

DTC P208B is a generic SAE powertrain code set when the Engine Control Module (ECM) or Selective Catalytic Reduction (SCR) controller detects that the reductant (AdBlue/DEF) pump output is outside its expected operating range. The pump is responsible for drawing diesel exhaust fluid from the tank and delivering it at controlled pressure to the dosing injector upstream of the SCR catalyst. When measured pump current draw, speed feedback, or pressure response deviates from commanded values, the control module flags a range/performance fault.

Common triggers include a worn or seized pump motor causing abnormal current draw, blockages in the reductant supply line or filter causing the pump to labour without reaching target pressure, and crystallised urea deposits restricting flow. Electrical faults — corroded pump connector pins, high-resistance wiring, or a failing pump relay — can produce the same performance deviation without any mechanical fault in the pump itself.

The fault typically illuminates the MIL and may trigger a NOx emissions warning lamp. On many vehicles a countdown timer starts: if the fault is not corrected within a set number of drive cycles, the ECM enforces a torque or speed derate.

Common causes

Most-frequently reported root causes when P208B is logged.

  • 1
    Faulty or seized reductant pump motor
  • 2
    Blocked reductant supply line, strainer, or pump inlet filter with urea crystal deposits
  • 3
    Reductant pump relay failed open or with high contact resistance
  • 4
    Corroded, damaged, or high-resistance wiring/connector at the reductant pump
  • 5
    Reductant tank run dry, causing pump to prime against air
  • 6
    Reductant pressure sensor fault producing incorrect feedback
  • 7
    Failed or contaminated reductant (wrong fluid type, diluted, or frozen DEF)
  • 8
    ECM/SCR controller internal fault or outdated software

Symptoms drivers notice

MIL (Check Engine light) illuminated
Reduced engine torque or speed limiter active (derate countdown reached threshold)
Increased NOx emissions and possible failure of emissions inspection
Reductant system warning message on instrument cluster
Audible pump not priming or running at startup in cold conditions
Possible hard start or refusal to restart if the derate has progressed

How to diagnose P208B

A typical diagnostic flow when this code is present.

  1. 1
    Connect a scan tool and record all active and pending DTCs
  2. 2
    Check reductant tank level and fluid quality
  3. 3
    Inspect the reductant pump connector and wiring harness for corrosion
  4. 4
    Measure pump supply voltage and ground at the connector with ignition on
  5. 5
    Activate the reductant pump via bi-directional scan tool controls
  6. 6
    Inspect the reductant supply line, filter, and strainer for blockages
  7. 7
    If wiring and mechanical components test good, check for ECM/SCR module software updates

Vehicles where we've handled P208B

Platforms in our catalogue with confirmed P208B coverage.

AUDI A4 20D
VW TRANSPORTER
AUDI A6
2015
AUDI A6 30D
2015
AUDI A7
AUDI A7 30D

Related powertrain codes

Frequently asked questions

Can I drive with P208B active?

Short distances are usually possible while the MIL is first illuminated, but many manufacturers implement a progressive derate.

Will topping up the AdBlue/DEF tank clear this code?

If the root cause was simply an empty tank causing the pump to run dry, refilling the tank and performing a pump prime cycle may allow the system to relearn.

Is P208B the same as P20E8 or P2047?

No. P208B relates to the pump control circuit range/performance. P20E8 and P2047–P204B describe faults in the reductant injector circuit.

How much does it typically cost to fix P208B?

A blocked filter or supply line flush is inexpensive. A full reductant pump assembly replacement typically costs €150–€400 in parts plus 1–2 hours labour.

Disabling P208B in software

RaceTune can permanently disable P208B — 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 P208B 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 EDC17C74 verified 2 software versions
  • Bosch EDC17CP44 verified 1 software version
  • Bosch MD1CP004 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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