P0313: Low fuel is part of the misfire context, not a complete diagnosis

Ford describes P0313 as misfire detected with low fuel level. That qualifier matters, but it does not prove that every irregular combustion event was caused by running out of fuel or that no other fault is present.

Keep fuel level with the misfire record

The documented misfire strategy calculates rates over 200- and 1,000-revolution windows. The shorter window concerns catalyst-damaging behavior, while the longer window supports an emissions-rate evaluation. Preserve fuel-level information alongside those rates, cylinder counts and operating conditions rather than treating the low-fuel label as a substitute for the actual misfire evidence.

The source's general entry table lists a fuel-level requirement, while the code list separately includes this low-fuel result. It does not spell out the complete low-fuel exception or a unique P0313 threshold. This article therefore does not assign a universal tank percentage at which P0313 must set.

Verification needs an active monitor

The monitor can be temporarily disabled during fuel cutoff, rough-road conditions or rapid torque changes. Learned crank-profile corrections and valid crank/cam information are also relevant. An interval with no new counts is meaningful only if evaluation was active.

After the low-fuel condition is addressed, retain the subsequent monitor result and any remaining cylinder-specific faults. The summary supports distinguishing low-fuel context from a demonstrated component cause; it does not authorize dismissing persistent misfire or replacing a pump solely from P0313.

Source and applicability

This explanation covers the cited Ford monitor variants, not every vehicle displaying this code. Match the engine, sensor architecture and calibration before applying numerical limits.

Ford OBD summary, PDF page 10, Ford OBD summary, PDF page 11.