Injector Control Pressure Too Low During Cranking
The P2291 code indicates that the Engine Control Module (ECM) has detected the injector control pressure (ICP) is below the minimum threshold required for starting the engine. This pressure is generated by the high-pressure oil pump in diesel engines (common in Ford Power Stroke and similar) to actuate the fuel injectors. During cranking, the ECM expects a certain ICP; if it's too low, the engine may not start or will have extended cranking times. Common causes include low engine oil level, faulty ICP sensor, high-pressure oil pump failure, or leaks in the high-pressure oil system.
1. Most Common Causes
- Low engine oil level or incorrect oil viscosity
- Faulty injector control pressure (ICP) sensor
- High-pressure oil pump failure or worn components
- Leaks in high-pressure oil system (e.g., injector O-rings, standpipes, dummy plugs)
2. Symptoms You Will Notice
- Engine cranks but does not start
- Extended cranking time before start
- Rough idle or misfire after start
- Check Engine Light illuminated
3. Step-by-Step Diagnosis
Step 1: Check engine oil level and condition; top off or change if necessary.
Step 2: Use a scan tool to monitor ICP sensor reading during cranking; compare to specified range (typically 500-1000 psi).
Step 3: Inspect for high-pressure oil leaks at injectors, standpipes, and dummy plugs using a leak-down test.
Step 4: Test the ICP sensor by checking voltage and resistance; replace if out of spec.
Step 5: If no leaks and sensor is good, evaluate high-pressure oil pump performance; replace if worn.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
No, it is not safe. The engine may stall or fail to restart, leaving you stranded. Have it diagnosed and repaired immediately.
How much does it cost to fix?▼
Cost varies: oil change $50-$100, ICP sensor $100-$200, high-pressure oil pump $500-$1500. Diagnostic fees are typically $100-$150.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.