P2C6A

Reductant Level Sensor Circuit Intermittent

P2C6A is a generic OBD-II powertrain diagnostic trouble code: Reductant Level Sensor Circuit Intermittent. 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
P2C6A
Group
Powertrain
System
Powertrain
Severity
Warning (MIL on)
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What P2C6A means

P2C6A is stored when the SCR or aftertreatment control module detects erratic or intermittent signal behaviour from the DEF level sensor circuit. Unlike the steady high or low circuit codes, P2C6A indicates that the signal is dropping in and out of the acceptable range, making level reporting unreliable without a consistent electrical open or short being present.

Intermittent electrical faults in DEF systems are often caused by connectors or terminals that have been partially degraded by DEF crystallisation, vibration-induced chafing of the wiring harness, or a failing sensor whose output flickers under thermal or vibration stress. The fault may not be present when the vehicle is stationary during a workshop inspection.

Diagnosis requires wiggle-testing the harness and connector while monitoring live sensor data, inspecting terminals for signs of corrosion or DEF residue, and checking for wiring chafe points along the harness routing. Capturing freeze frame data or using a data logger during a road test can help reproduce the fault.

Common causes

Most-frequently reported root causes when P2C6A is logged.

  • 1
    Intermittent connection at the DEF tank sender connector due to corrosion.
  • 2
    Loose or spread terminal pin in the sensor connector.
  • 3
    Chafed wiring harness making and breaking contact with chassis or exhaust.
  • 4
    Failing DEF level sensor with unstable internal output.
  • 5
    Vibration-sensitive break in the signal wire.
  • 6
    DEF crystallisation partially bridging connector terminals.
  • 7
    Loose sensor mounting causing intermittent mechanical movement.

Symptoms drivers notice

MIL or SCR lamp illuminated, possibly cycling on and off.
Fluctuating or erratic DEF level reading on the instrument cluster.
Intermittent low-DEF warnings that do not correspond to actual tank level.
Fault may not be present during static diagnosis.
Possible entry into SCR degraded mode during fault events.

How to diagnose P2C6A

A typical diagnostic flow when this code is present.

  1. 1
    Retrieve all DTCs; note if companion high or low circuit codes are also stored.
  2. 2
    Monitor live DEF level sensor voltage while wiggling the harness and connector to try to reproduce the fault.
  3. 3
    Inspect connector terminals for corrosion, DEF residue, or loose pins.
  4. 4
    Trace the harness from the DEF tank to the control module and check for chafe points.
  5. 5
    Clean and re-pin corroded terminals if found; apply dielectric grease after repair.
  6. 6
    Perform a road test with live data monitoring to capture the intermittent fault.
  7. 7
    Replace sender unit if terminal and wiring repairs do not resolve the intermittent.

Vehicles where we've handled P2C6A

Platforms in our catalogue with confirmed P2C6A coverage.

BMW 320D
2016

Related powertrain codes

Frequently asked questions

Why is an intermittent code harder to diagnose than a steady fault?

The fault condition is not always present, so voltage and continuity tests during a static inspection may pass even when a real problem exists under vibration or thermal stress.

Is wiggle-testing safe on DEF system wiring?

Yes, gentle manipulation of the harness and connectors during live monitoring is a standard diagnostic technique and does not harm the system.

Can a DEF quality sensor fault look like P2C6A?

No, quality and level sensors have separate DTCs; P2C6A is specific to the level sensor circuit.

Will cleaning the connector fix this fault?

Cleaning corroded terminals and applying dielectric grease resolves many intermittent DEF sensor faults, particularly on vehicles with high mileage or exposure to road spray.

Disabling P2C6A in software

RaceTune can permanently disable P2C6A — 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 P2C6A 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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