P2C68

Reductant Level Sensor Circuit High

P2C68 is a generic OBD-II powertrain diagnostic trouble code: Reductant Level Sensor Circuit High. 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
P2C68
Group
Powertrain
System
Powertrain
Severity
Warning (MIL on)
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What P2C68 means

P2C68 is stored when the SCR or aftertreatment control module detects that the DEF level sensor signal voltage exceeds the maximum acceptable threshold. This is the electrical complement to P2C67, indicating an open circuit, short to voltage, or a failed sensor whose output is near or above the supply rail rather than within the normal operating range.

With an abnormally high sensor signal, accurate DEF level reporting is impossible. The system cannot determine whether the tank needs to be refilled and cannot provide reliable low-level warnings to the driver. Regulatory derate logic treats persistent reductant sensor faults as seriously as actual low DEF conditions in many calibrations.

Diagnosis should focus on the signal wire between the sensor and control module for shorts to a voltage source, on the sensor ground return path for opens, and on the sensor itself for an internal failure. Connector inspection is important as DEF is corrosive and can damage terminals over time.

Common causes

Most-frequently reported root causes when P2C68 is logged.

  • 1
    Open circuit in the DEF level sensor signal wire.
  • 2
    Sensor signal wire shorted to a 5V reference or 12V supply.
  • 3
    Failed DEF level sensor with output stuck high.
  • 4
    Open sensor ground return circuit.
  • 5
    Corroded connector terminals causing floating or elevated signal.
  • 6
    DEF fluid contamination of connector causing resistive short to supply.
  • 7
    Faulty control module input circuit for the level sensor.

Symptoms drivers notice

MIL or SCR warning lamp illuminated.
Inaccurate DEF level indication, possibly showing full at all times.
Driver may miss actual low DEF condition without warning.
Risk of regulatory torque derate if the fault persists.
SCR system operating in degraded or default mode.

How to diagnose P2C68

A typical diagnostic flow when this code is present.

  1. 1
    Scan all modules for DTCs and note companion reductant system codes.
  2. 2
    Verify live DEF sensor voltage reads above the maximum calibrated limit.
  3. 3
    Inspect the DEF tank sender connector for corrosion and DEF residue on terminals.
  4. 4
    Check sensor ground path continuity from sensor back to module ground.
  5. 5
    With sensor disconnected, measure voltage on the harness signal wire; any reading indicates a short to supply.
  6. 6
    Test sensor output resistance or voltage in isolation to confirm or rule out internal failure.
  7. 7
    Repair wiring or replace the sender unit as indicated.

Vehicles where we've handled P2C68

Platforms in our catalogue with confirmed P2C68 coverage.

BMW 320D
2016

Related powertrain codes

Frequently asked questions

Why would DEF fluid cause connector problems?

DEF is a urea-water solution that can crystallise around connectors and corrode terminals, increasing contact resistance or causing unexpected voltage readings.

Can P2C68 be set if the DEF tank is overfilled?

No. An overfill condition does not cause a high electrical circuit code; P2C68 is an electrical fault unrelated to actual fluid level.

How urgent is P2C68 compared to a genuine low DEF warning?

Both require attention. The electrical fault means the system cannot monitor DEF level at all, so the driver is effectively flying blind on DEF quantity.

Can I check the sensor without removing the DEF tank?

Yes, on most vehicles the sender connector is accessible without tank removal; electrical tests can be performed at the connector before committing to sender replacement.

Disabling P2C68 in software

RaceTune can permanently disable P2C68 — 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 P2C68 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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