Failure mode - Ford 6.0L Power Stroke

IPR (Injection Pressure Regulator) valve failure

Reliability tier: verified - verify before ordering, see /disclosure/

Symptoms

hard start, no-start, or stall at idle
surge / hunt at idle
ICP actual not tracking ICP desired
IPR duty cycle pegged high or low; ICP / IPR fault codes

Root cause

The IPR valve on the high-pressure oil pump controls injection control pressure. Its screen clogs, the valve wears or sticks, and its o-rings / edge filter fail, so it cannot regulate ICP. A related early-build issue is a faulty ICP sensor giving a false pressure signal.

Diagnosis

scan tool: compare ICP actual vs desired and IPR duty %
IPR duty roughly 8-15% at warm idle is normal; consistently above ~30-40% or pegged suggests a high-pressure oil leak or a failing IPR
inspect the IPR screen and o-rings

Fixes

clean or replace the IPR valve with a new screen and o-rings ()

ipr-valve (part category - specific model not chosen)

check for upstream high-pressure oil leaks (STC fitting, standpipes, HPOP) that make the IPR overwork ()

stc-fitting-kit (part category - specific model not chosen)

Prevalence

common