P0505: Maxima idle-air diagnosis includes learning and two fault branches

P0505 in the 2001 Nissan Maxima manual concerns the auxiliary idle-air control valve. A step motor changes the bypass-air opening so the engine controller can bring actual idle speed toward its stored target while accounting for changing loads.

The displayed step value is a command context

Nissan supplies a warm, unloaded idle reference with accessories and selector position specified. A step count observed with air conditioning or steering load present cannot be compared blindly with that unloaded reference. The valve's commanded opening changes with the amount of bypass air required.

The document distinguishes two malfunction branches. Its possible-cause lists associate the first with an open circuit and the second with a short, while also naming the valve and, for the second branch, the power-steering air-control valve.

Check the learning prerequisite

If target idle speed is outside specification, Nissan calls for idle-air-volume learning before the confirmation procedure. That is not a promise that relearning will repair an electrical fault. It is a prerequisite for evaluating the system under the intended conditions.

The confirmation sequence attempts the first branch before the second, and the electrical diagnosis begins with the valve's supply circuit. A failed idle symptom alone does not identify which branch applies.

Record the target and actual idle behavior, operating loads, learning status and circuit findings. A successful repair needs the appropriate confirmation result, not simply an idle speed that temporarily improved after clearing memory.

Documented application

2001 Nissan Maxima, EC section. Exact engine, drivetrain and diagnostic applicability must be checked in the cited procedure.

Source

2001 Nissan Maxima Factory Service Manual: EC, physical PDF pages 429, 430, 431, 433, 437.