P2291: Injector Control Pressure Too Low Engine Cranking
Do not keep driving
The engine cranks normally and will not fire. Tell whoever looks at it that the injectors on this engine are driven by engine oil pressure, not by the fuel pump — this fault looks exactly like fuel starvation, and filters, pumps and injectors get replaced for it while the actual problem is in the oil circuit. Check the oil level yourself first, and say when it was last changed and with what grade. Slightly low or degraded oil is a genuinely common cause of this no-start, and it is free to rule out. If the engine starts fine when warm and only fails cold, say so — that points at oil condition rather than at a failed pump.
What this code means
There is not enough injection control pressure while cranking for the injectors to fire. This is the no-start code on a hydraulically actuated system, and it is the reason the whole family is worth understanding.
These injectors have a threshold. Below a minimum pressure — commonly a few hundred psi — they do not partially inject or inject weakly. They do not fire at all. So the engine cranks normally, sounds entirely healthy, has fuel, has compression, has a working starter, and does not start. Nothing about the symptom points at oil.
Which is exactly why this is the expensive one. The picture reads as fuel starvation, so fuel filters get changed, lift pumps get replaced, injectors get condemned, and the fault is in a circuit nobody looked at. The single most useful thing an owner can say to a workshop faced with this is that the injectors on this engine are driven by oil pressure.
The cheap causes come first and are genuinely common:
- Oil level too low to prime the system. The reservoir feeding the high-pressure pump needs to be full; slightly low oil is enough to prevent a cold start while the engine still runs once going.
- Oil too thick or too degraded to move quickly enough during cranking, which is why these engines characteristically start poorly cold and fine warm, and why the fault appears in winter or after a missed service.
- Air in the high-pressure circuit, typically after any repair that opened it, which prevents pressure building until it is purged.
Then the mechanical ones: an internal leak in the high-pressure oil circuit, a regulator that cannot hold pressure, and last a worn pump.
A cold-start-only version of this fault is a strong signal. Starts fine warm, will not start cold, means the system can make pressure but not quickly enough with thick oil — which points at oil condition and at marginal leakage rather than at a dead pump.
Likely causes
Start here
- Low engine oil level · easy
- Incorrect oil grade or degraded oil · easy
- Leak in the high-pressure oil circuit · specialist
Less common
- Air in the high-pressure oil circuit · moderate
- Faulty injection pressure regulator · moderate
- Worn high-pressure oil pump · specialist
- Faulty injection control pressure sensor · moderate
Symptoms
Components involved
Information, not instruction
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Community experience
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