📘 Code P2291 – Injector Control Pressure Too Low at Engine Start
How Severe Is This DTC Code?
Code P2291 is considered severe. It indicates that the pressure in the injector control circuit is insufficient, especially during startup. This situation can prevent the engine from starting properly or lead to serious damage, particularly in high-pressure diesel engines. It is therefore essential to address this issue immediately.
🔍 Symptoms Associated with Code P2291
Among the signs indicating the presence of this code, you may observe:
- Inability to start the engine
- Excessive exhaust smoke
- Unusual sounds from the engine
- Loss of power or irregular operation
🔧 Common Causes of Code P2291
This code can result from various mechanical or electrical issues. Here are the most common ones:
General Causes:
- Faulty high-pressure fuel pressure sensor
- Open, damaged, or short-circuited electrical circuit
- Insufficient engine oil level
- Low engine oil pressure
Specific Causes (e.g., Peugeot):
- Air leak in the fuel circuit: loose fittings, damaged fuel filter, punctured line
- Clogged fuel filter: restricts fuel supply to the pump
- Running out of fuel: always check the fuel level
- Faulty fuel pressure regulator: unable to maintain correct pressure
- Failed high-pressure fuel pump: does not deliver the pressure required for injection
- Leak in the high-pressure circuit: faulty injectors, rails, or lines
- Electrical problem: damaged pressure sensor, wiring, or connectors
🛠️ Diagnostic and Repair Steps
- Check the engine oil level and ensure no oil pressure or level warning lights are on.
- Perform an oil pressure test if necessary. Low pressure can affect variable valve timing (VVT) and injection pressure.
- Use an OBD2 scanner and a digital multimeter (DVOM), along with a reliable technical information source (RTA, TSB, etc.).
🧰 Detailed Procedure:
- Look for any technical service bulletins (TSB) related to your vehicle.
- Connect the scanner, retrieve codes and freeze frame data, then clear the codes to see if they return.
- If the code returns immediately, continue diagnostics. Otherwise, it may be intermittent and require monitoring over time.
- Visually inspect wiring and connectors related to the injection system. Repair any damaged, burnt, or loose cables.
- Test the power and ground circuits of the pressure sensor using the DVOM. Also check associated fuses.
- If the power supply is correct, test continuity between the sensor and the PCM (engine control module).
- If voltage is present at the PCM but the code persists, suspect a software issue or a faulty PCM.
- Test the injection pressure sensor: compare the obtained values with manufacturer specifications.
💡 Practical Tips:
- You can reset the code temporarily by disconnecting the battery for a few minutes. Note that this only clears the code, not the problem.
- If you are skilled in mechanics, you can perform the checks yourself. Otherwise, consult a qualified professional.
- Do not drive for long with this code active: it could cause irreversible engine damage.
🔚 In Conclusion
Code P2291 is a clear indicator of a fuel pressure issue during startup, often encountered in modern diesel engines. When faced with this code, prompt and thorough diagnostics are essential to avoid costly repairs or even engine failure.