P2F93

Reductant Injection System Pressure Too Low

P2F93 is a generic OBD-II powertrain diagnostic trouble code: Reductant Injection System Pressure Too Low. 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
P2F93
Group
Powertrain
System
Powertrain
Severity
Warning (MIL on)
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What P2F93 means

P2F93 is set when the PCM or SCR control module detects that the reductant system pressure is below the minimum threshold required for proper DEF injection into the exhaust. Adequate pressure is necessary to atomize the reductant correctly and ensure even distribution across the SCR catalyst face.

Common causes include a failing reductant pump, a pump filter clogged with crystallized urea deposits, or a leak in the pressurized supply line between the pump and the injector. The system typically uses a pressure sensor to provide closed-loop feedback; if pressure cannot be built or maintained during a dosing event, this fault is triggered.

Low reductant pressure results in under-dosing, which elevates tailpipe NOx emissions and may eventually set NOx efficiency codes as well. Addressing this fault early prevents compounding faults and potential inducement strategies that restrict vehicle speed or engine output.

Common causes

Most-frequently reported root causes when P2F93 is logged.

  • 1
    Reductant pump failing to generate sufficient pressure.
  • 2
    Pump inlet filter clogged with crystallized DEF deposits.
  • 3
    Leak in the reductant high-pressure supply line.
  • 4
    Reductant pressure sensor failed low (giving false low reading).
  • 5
    Frozen reductant line in cold climates if the heating element has failed.
  • 6
    Check valve in the pump assembly stuck open, preventing pressure build.
  • 7
    Low DEF level in the tank causing pump cavitation.

Symptoms drivers notice

MIL and SCR warning light illuminated.
Possible engine derate or inducement if fault persists across multiple drive cycles.
Increased NOx emissions detectable on emissions test.
Audible pump noise changes during reductant priming cycle.
DEF consumption lower than expected.

How to diagnose P2F93

A typical diagnostic flow when this code is present.

  1. 1
    Read and record all DTCs and freeze frame data with a scan tool.
  2. 2
    Check DEF tank level; refill if low.
  3. 3
    Inspect the reductant pump inlet filter for crystallized deposits and clean or replace as needed.
  4. 4
    Use scan tool live data to monitor reductant pressure during a pump priming command.
  5. 5
    Inspect high-pressure lines and fittings for leaks or damage.
  6. 6
    Test the reductant pressure sensor output against known specification.
  7. 7
    If pump fails to build pressure after filter service, replace the reductant pump assembly.

Related powertrain codes

Frequently asked questions

Can a clogged filter cause P2F93?

Yes, crystallized urea in the pump inlet filter is one of the most common causes of low reductant pressure.

Is P2F93 the same as P2F92?

No. P2F92 is a general performance fault while P2F93 specifically identifies pressure as being too low.

Will a DEF line freeze cause this code?

Yes. If the heating element in the reductant line fails, the DEF can freeze in cold weather, preventing pressure build-up.

Can I top up the DEF tank to clear P2F93?

If low level caused pump cavitation, refilling may resolve it. However, if the pump or filter is faulty the code will return.

Disabling P2F93 in software

RaceTune can permanently disable P2F93 — 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 P2F93 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.

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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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