P2991

Fuel Rail Pressure Too High - Engine Cranking

P2991 is a generic OBD-II powertrain diagnostic trouble code: Fuel Rail Pressure Too High - Engine Cranking. 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
P2991
Group
Powertrain
System
Powertrain
Severity
Warning (MIL on)
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What P2991 means

P2991 is set when the powertrain control module (PCM) detects that fuel rail pressure is above the expected threshold while the engine is in a cranking condition. During cranking, the fuel system should build pressure within a calibrated ramp; an excessively high reading at this point suggests a pressure regulation fault.

Common causes include a stuck-open high-pressure fuel pump, a faulty fuel pressure regulator that is not bleeding pressure appropriately, or a leaking high-pressure injector that allows backflow. The PCM compares actual rail pressure sensor output against the commanded target and flags the code when the measured value exceeds the upper limit for the cranking phase.

Driving with this fault may result in hard starting, rough idle immediately after start, or minor misfires as the injectors are presented with higher-than-intended differential pressure. Diagnosis should begin with reading live fuel rail pressure data during cranking before any component replacement is attempted.

Common causes

Most-frequently reported root causes when P2991 is logged.

  • 1
    High-pressure fuel pump delivering excessive flow due to internal regulator failure.
  • 2
    Fuel pressure regulator mechanically stuck in the closed or low-bleed position.
  • 3
    Faulty fuel rail pressure sensor providing an erroneously high voltage signal.
  • 4
    Wiring short to voltage on the fuel rail pressure sensor signal circuit.
  • 5
    Check valve in the high-pressure pump not seating correctly, trapping pressure.
  • 6
    PCM calibration or software issue causing incorrect pressure target during crank.

Symptoms drivers notice

Hard starting or extended crank time before the engine fires.
Rough idle immediately after a cold start.
MIL (check engine light) illuminated.
Occasional engine stumble during initial throttle tip-in after start.
Fuel smell near the engine bay in severe cases.

How to diagnose P2991

A typical diagnostic flow when this code is present.

  1. 1
    Connect a scan tool and record all stored codes and freeze-frame data before clearing anything.
  2. 2
    Monitor live fuel rail pressure PID during cranking and compare to manufacturer specification.
  3. 3
    Inspect the fuel rail pressure sensor connector and wiring for corrosion, damage, or a short to voltage.
  4. 4
    Substitute a known-good pressure sensor or perform a sensor reference voltage and ground check.
  5. 5
    Test fuel pressure regulator operation and bleed-down rate using manufacturer procedures.
  6. 6
    Check high-pressure fuel pump delivery pressure against specification with a calibrated gauge.
  7. 7
    If all mechanical readings are within spec, check for a PCM software update addressing fuel pressure targets.

Vehicles where we've handled P2991

Platforms in our catalogue with confirmed P2991 coverage.

BMW 320D
2016

Related powertrain codes

Frequently asked questions

Can I drive with P2991 active?

Short-term driving is generally possible, but hard starting and rough idle may worsen. Diagnose promptly to avoid injector or pump damage from sustained over-pressure.

Will clearing the code fix the problem?

No. The code will return on the next crank event if the underlying pressure regulation fault is not corrected.

Is the fuel rail pressure sensor the most likely cause?

A faulty sensor is one possibility, but always verify actual rail pressure with an independent gauge before condemning the sensor.

Does this code affect only direct-injection engines?

P2991 is most commonly associated with gasoline direct injection (GDI) systems where a high-pressure pump operates above the low-pressure supply, but it can appear on any system with a monitored fuel rail pressure sensor.

Disabling P2991 in software

RaceTune can permanently disable P2991 — 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 P2991 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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