P2561

Reductant Level Sensor Circuit Range/Performance

P2561 is a generic OBD-II powertrain diagnostic trouble code: Reductant Level Sensor 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
P2561
Group
Powertrain
System
Powertrain
Severity
Warning (MIL on)
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What P2561 means

P2561 is set when the reductant level sensor signal is within the normal electrical operating range but does not correlate with expected system behaviour or known physical conditions. This distinguishes it from P2560, which indicates a hard electrical fault. A range/performance fault suggests the sensor is producing a plausible but incorrect signal.

Typical causes include a partially failed sensor that produces a slow or stuck reading, sloshing of the DEF fluid during vehicle manoeuvres causing transient signal implausibility, or contamination of the reductant fluid altering the dielectric properties sensed by a capacitive sensor. Wiring intermittent issues such as a high-resistance connection can also produce a signal that is electrically valid but systematically offset.

Because the level signal is used to manage driver warnings and to enforce derate countdowns on empty-tank conditions, an inaccurate performance fault is taken seriously by the ECM. Dosing may continue but with reduced confidence in the level reading, and a derate may be triggered prematurely or fail to trigger when the tank is genuinely empty.

Common causes

Most-frequently reported root causes when P2561 is logged.

  • 1
    Partially failed or slow-responding reductant level sensor.
  • 2
    Stuck or sticking float mechanism in a float-type level sender.
  • 3
    High-resistance connection in the sensor circuit causing signal offset.
  • 4
    Contaminated or degraded DEF affecting capacitive sensor calibration.
  • 5
    Sensor calibration drift after extended service life.
  • 6
    Air bubble or foam in the DEF tank affecting sensor output.
  • 7
    Wiring intermittent causing occasional incorrect readings flagged as performance fault.

Symptoms drivers notice

MIL illuminated with P2561 stored.
Reductant level gauge reading that does not change or changes erratically.
Level reading does not update after a known refill of DEF.
Possible false low-level warning or no warning when tank is empty.
SCR dosing may continue but with flag set on level data reliability.

How to diagnose P2561

A typical diagnostic flow when this code is present.

  1. 1
    Connect a scan tool and record all DTCs along with freeze frame and live level sensor data.
  2. 2
    Monitor the reductant level sensor reading during a drive and after refilling the tank to check for rational response.
  3. 3
    Inspect DEF quality; test with a DEF refractometer if contamination is suspected.
  4. 4
    Check connector terminals for high resistance using a milliohm-level measurement.
  5. 5
    Inspect the tank module for physical damage to the float or sensor element.
  6. 6
    Compare sensor output against a known-good reference tank level if possible.
  7. 7
    Replace the DEF tank module or sender if sensor response is confirmed sluggish or stuck.

Vehicles where we've handled P2561

Platforms in our catalogue with confirmed P2561 coverage.

BMW 320D
2016

Related powertrain codes

Frequently asked questions

Why does P2561 appear even though my level gauge looks normal?

The gauge may be rounding or averaging values in a way that hides the actual sensor signal fault; scan tool live data will show the raw signal more accurately.

Can wrong DEF quality cause P2561?

Yes. Contaminated or diluted DEF can alter the signal from a capacitive sensor enough to trigger a performance fault.

Is P2561 more serious than P2560?

Both require attention. P2560 is a hard circuit fault, while P2561 is a performance issue. Either can compromise accurate level monitoring.

Will topping up the DEF tank clear P2561?

If the fault was caused by foam or air affecting the sensor transiently, topping up and allowing the fluid to settle may help, but a persistent code indicates a sensor or wiring issue.

Disabling P2561 in software

RaceTune can permanently disable P2561 — 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 P2561 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 EDC17C50 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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