P24CE

Reductant Injection Quantity Too High

P24CE is a generic OBD-II powertrain diagnostic trouble code: Reductant Injection Quantity Too 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
P24CE
Group
Powertrain
System
Powertrain
Severity
Warning (MIL on)
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What P24CE means

P24CE is set when the ECM determines that the actual DEF injection quantity exceeds the demanded dosing amount. The dosing control system monitors flow feedback, pressure decay, and dosing module command versus response, and logs this fault when delivered quantity is persistently above the calibrated upper limit for a given operating condition.

Over-dosing DEF can lead to ammonia slip past the SCR catalyst, which is itself an emissions violation and can damage downstream components such as an ammonia slip catalyst (ASC) or cause ammonia odor in the exhaust. In some cases, the excess DEF can condense in the exhaust and cause urea deposits further downstream.

The most common causes include a stuck-open or leaking dosing module, incorrect DEF pressure calibration causing over-delivery, or a faulty dosing module driver providing excessive pulse width. Diagnosis should include a dosing module leak-down test and live data review of dosing demand versus actual flow. The DEF pressure should also be verified to ensure it is not above the calibrated upper limit.

Common causes

Most-frequently reported root causes when P24CE is logged.

  • 1
    Stuck-open or leaking DEF dosing module injector.
  • 2
    Excessive DEF supply pressure above the calibrated upper limit.
  • 3
    Faulty dosing module driver circuit providing incorrect pulse width.
  • 4
    DEF pressure sensor fault causing the ECM to miscalculate delivery.
  • 5
    Software calibration fault in dosing control strategy.
  • 6
    Dosing module needle valve wear causing over-delivery.

Symptoms drivers notice

MIL illuminated.
Ammonia smell from the exhaust.
White crystalline deposits in the exhaust pipe downstream of the dosing point.
Possible additional NOx or ammonia slip sensor codes.
No immediate drivability change in most cases.

How to diagnose P24CE

A typical diagnostic flow when this code is present.

  1. 1
    Connect a scan tool and retrieve all DTCs and freeze frame data.
  2. 2
    Review live DEF dosing demand versus actual quantity delivered.
  3. 3
    Check DEF supply pressure against specification; verify pressure regulator function.
  4. 4
    Perform a dosing module leak-down test by commanding the pump off and monitoring pressure hold.
  5. 5
    Inspect the dosing module for signs of leakage or crystallization around the tip.
  6. 6
    Check the dosing module driver circuit for correct pulse width output.
  7. 7
    Replace the dosing module if it fails the leak-down test or shows internal leakage.

Vehicles where we've handled P24CE

Platforms in our catalogue with confirmed P24CE coverage.

BMW 320D
2016

Related powertrain codes

Frequently asked questions

Is over-dosing DEF harmful to the SCR catalyst?

Yes. Chronic over-dosing causes ammonia slip, which can saturate and damage the SCR substrate and any downstream ammonia slip catalyst. It also produces an ammonia odor in the exhaust.

Can high DEF pressure cause P24CE?

Yes. If line pressure is above the designed operating range, the dosing module will deliver more fluid per command pulse than calibrated, resulting in an over-quantity condition.

Does P24CE mean my DEF system is wasting fluid?

Yes. Excess DEF is being delivered, which means the tank will empty faster than expected and conversion efficiency may not improve proportionally, since excess ammonia passes through unconverted.

Can an ECM software update fix P24CE?

If the root cause is a calibration error in the dosing control strategy, a software update may resolve the issue. Always check for applicable technical service bulletins before replacing hardware.

Disabling P24CE in software

RaceTune can permanently disable P24CE — 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 P24CE 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
  • Bosch EDC17CP09 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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