Cause
Air drawn into the fuel supply
Air entering the fuel circuit and reaching the high pressure pump, which cannot compress it. A diesel injection system depends on fuel being incompressible; air in the circuit means the pump strokes without building pressure, and the result is a long crank, a rough start or a stall that clears once the system purges itself.
It differs from a suction-side leak in scope rather than in kind. A leak draws air continuously under vacuum; this entry covers the broader case, including air left after a filter change that was never bled, a tank run genuinely empty, or a system opened for repair and closed without priming. The timing is the strongest clue — a fault that begins immediately after fuel work is air until proven otherwise.
Bleeding is the repair and finding the entry point is the diagnosis, and skipping the second means doing the first repeatedly. Many systems self-bleed given enough cranking, which is exactly why a genuine leak hides: the vehicle recovers each time and the fault reads as intermittent. Check whether it returns after standing — air that reaccumulates overnight is coming in somewhere, and air that never returns was simply left behind.
Typically a moderate job.
Some of these codes mean you should stop driving
1 of the 6 codes this can cause indicate a fault where continuing to drive risks damage or is unsafe. Which one you have matters more than the cause does — read the code's own page before deciding.
Codes this can cause (6)
Codes where this is a likely explanation first, rather than merely a possible one.
- P008A Low Pressure Fuel System Pressure - Too Low High
- P00C6 Fuel Rail Pressure Too Low - Engine Cranking Bank 1 High
- P016F Closed Loop Fuel Pressure Control At Limit - Pressure Too Low High
- P2293 Fuel Pressure Regulator B Performance High
- P2540 Low Pressure Fuel System Sensor Circuit Range/Performance Stop driving High
- P2672 Injection Pump Timing Offset High
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
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