P2291
Injector Control Pressure Too Low - Engine Cranking
Fuel injection (diesel)
Generic OBD-II
High
What it means
P2291 is a diesel code (HEUI-type injection, such as Ford Power Stroke) meaning injector control pressure — the high-pressure oil that fires the injectors — is too low while the engine is cranking. Without enough control pressure the injectors can't deliver fuel, so the engine cranks but starts hard or won't start at all. It usually points to a high-pressure oil system leak, low oil, or a pump/IPR fault.
High
Can I keep driving? Often a hard-start or no-start — the injectors need this pressure to fire, so the engine may crank without starting until the cause is fixed.
Common symptoms
What you'll notice
- Long cranking, hard starting, or a no-start
- Check-engine light on
- Stalling shortly after start
- Rough running or misfire at low rpm
Common causes
Most likely first
- Low, contaminated, or wrong-viscosity engine oil (the high-pressure oil pump uses engine oil)Likely
- High-pressure oil system leak (IPR valve, stand-pipes, o-rings, couplings)Common
- Faulty high-pressure oil pump (HPOP) or injection pressure regulator (IPR)Common
- Faulty injector control pressure (ICP) sensor or wiring reading lowLess often
- Weak batteries or slow cranking speedLess often
How to diagnose & fix
Work through it in order
- Check engine oil level and condition first; correct the viscosity if wrong.
- Scan live ICP data while cranking and compare against the specified pressure.
- Inspect the high-pressure oil system for leaks (IPR, stand-pipes, o-rings).
- Test the ICP sensor and its wiring/connector.
- Verify battery and cranking speed; test the HPOP and IPR if pressure stays low.
FAQ
Quick answers
Is it safe to drive with P2291?+
Often the engine won't start at all. If it does start, driveability is poor — have the high-pressure oil and injection system checked before relying on the vehicle.
Can I just clear P2291?+
Clearing has no lasting effect — until control pressure is restored the engine will keep hard-starting or failing to start.
Related codes
Often seen with P2291
Read & clear P2291 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX