P2291

Injector Control Pressure Too Low - Engine Cranking

Q: 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.

Q: 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.

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.

Real-world scan data

Seen in

130

scans in the past year

Found in

<0.1%

of scans

<0.1%

of scans that found faults

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

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.

Read & clear P2291 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX