# Codebook — high idle complaints (P0507 study)

Written before any complaint in the set was coded. Pool: every NHTSA complaint whose
narrative names an idle control code (P0505, P0506, P0507, including spellings with a
letter O, a space, a two-character suffix, or a bare number after the word "code"), or
uses a high-idle phrase ("high idle", "idles high", "idle at 1,500/2,000...", "racing idle",
"idle speed is high", and similar).

For each complaint record exactly one CATEGORY and three yes/no FLAGS.

## RELEVANCE comes first
N — Not about a high idle. The phrase matched but the complaint is not about the engine
    idling faster than normal (for example "surging" while driving at speed, "high" and
    "idle" in unrelated sentences, an idle that is too LOW or rough only, a stall only,
    stop-start behaviour only, or a complaint that only lists P0506 as "idle too low"
    with no high-idle event). A complaint that names P0505 or P0507 is never N.
    A complaint that names P0506 is N unless it also describes a high or racing idle.

## CATEGORY for relevant complaints (one letter)

T — Throttle or idle air: the electronic throttle body, idle air control valve, throttle
    position sensor or accelerator pedal sensor is diagnosed, cleaned or replaced, OR the
    complaint names a throttle code (P2101, P2111, P2112, P2119, P2135, P0121-P0123,
    P2122-P2138).

V — Air or vacuum leak: an intake or vacuum leak, PCV valve or hose, brake booster
    hose/check valve, intake manifold gasket or cracked intake is diagnosed or repaired.

C — Computer or software: engine computer reprogrammed/updated/replaced, an idle relearn
    or reset is the stated fix, or a recall/bulletin software update is performed for it.

E — Other engine or sensor cause stated: coolant temperature sensor, alternator/charging,
    a cooling fan, a fuel/injector, a transmission or AC input, or any other named cause
    that is not T, V or C.

A — Vehicle moved by itself, no cause found: the complaint's main point is the vehicle
    lurching, surging forward or accelerating with the high idle (including crashes), and
    no cause is stated or the dealer "could not duplicate".

U — High idle described, no cause stated, and the vehicle is not described as moving
    by itself.

Precedence among causes: a stated diagnosis or repair wins (T, V, C, E); if several,
the one described as the fix wins; if still tied, the first one named. A beats U.
A stated cause beats A (a lurching car with a diagnosed throttle body is T, with the
moved_by_itself flag yes).

## FLAGS (yes/no)

moved_by_itself — the vehicle lurched, crept hard, surged forward or accelerated
    without the driver asking, OR the driver had to stand on the brake to hold it,
    because of the high idle.

crash — the complaint says the vehicle hit something or someone, or was hit, in this event.

light_on — the complaint says the check engine light (or a named code) came on.

## Output
One line per complaint, in the order given:
odino,category,moved_by_itself,crash,light_on,note
category is one of N T V C E A U. For N, write no for all flags.
note = at most 12 words, no commas, saying what drove the category.

## Codebook fixed before coding
2026-09-26T14:30:27Z
a9ba00ee2e74cc8bf1b22194528f3ebc7e2c20e94605acef563a8caf7d3eaa87  p0507/codebook.md

## Adjudication rules (written after the two readings, applied to every disagreement)
R1  An idle that only hunts "up and down", "surges" or "fluctuates", with no statement that it sits above normal
    (no "high", no elevated rpm figure), is N. "High and low" or a stated rpm above normal is relevant.
R2  An engine revving while driving because a transmission slips or will not shift is N, unless the narrative also
    describes a high idle at a standstill.
R3  A repair aimed at the high idle counts as a stated cause even if it did not work (codebook: a stated diagnosis
    or repair wins).
R4  A hedged owner guess ("I believe", "as if", "unsure") or a parts-store printout suggestion is not a stated cause.
R5  (written after the second reading, for complaints added by the completeness audit) Unintended acceleration while
    the car is moving is N, even if the engine races in neutral while the car still rolls; it is relevant only when
    the engine races at a standstill, in park or neutral, or right after a restart.
Each resolved complaint carries the rule in the rule_applied column of p0507-1241-complaints-read.csv.

## Pool history
The first search (the phrase list above) found 365 complaints. An independent audit of the complaint file then
searched for wordings the first search missed ("the idle is high", "races at idle", an rpm figure next to "at a
stop" or "in park", owner spellings such as IDOL or IDEAL, and a bare "code 507"); every complaint the widened
search matched, plus the audit's further cases, was added — 876 more — and coded by the same two readers
from this same codebook, blind to each other. Complaints the widened search caught that are not about a high idle
were coded N. The found_by column says which search found each complaint.