Cause
Low fuel supply pressure
Pressure on the low pressure side of the fuel system below what the high pressure pump needs to work with. It is a supply fault reported by the high pressure system, which is what makes it worth naming: the codes name rail pressure or injection, and the shortfall is upstream of all of it.
A high pressure pump cannot make up for a poor feed. Starved, it cavitates, fails to reach commanded rail pressure, and wears rapidly — so a lift-side problem left alone becomes an expensive one. Rail pressure that falls short under load with the pump at maximum duty is the pattern to recognise, and it is the module telling you it is asking for everything and not getting it.
The causes run in a clear order of likelihood: a blocked filter, a restricted or collapsed line, a weak transfer pump, a strainer blocked in the tank, or air drawn in on the suction side. Measure supply pressure at the high pressure pump's inlet — that single reading separates a lift-side problem from a high-side one and decides which half of the system to work on.
Typically a moderate job.
Codes this can cause (3)
Codes where this is a likely explanation first, rather than merely a possible one.
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
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.
Others who found this
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
Sign in or create an account to add what you found about Low fuel supply pressure.