SORTING RULES - MASS AIR FLOW (MAF) SENSOR CIRCUIT COMPLAINTS (P0103 / P0102 / P0100 / P0104)
PulsCar analysis of NHTSA public data, October 2026. License: CC BY 4.0

Fingerprint of the rules text below, taken when it was written and before any complaint was sorted: 548a653117ec8a7654d88e3ec2ccc4e1ee6431004384c469de7b076b2e37f8ce (2026-10-14T04:05:51Z)


Written before any complaint in the set was sorted.

## Pool (how the complaints were found)
NHTSA complaints received 2015-01-01 to 2026-10-04 (782,908 narratives; 2026-10-04 is the latest received date in the
flat files). A complaint is in the pool if its narrative matches either of the following case-insensitive text searches
(the second also needs one of its context words somewhere in the same narrative):

1. R1 - a MAF circuit code by any spelling (letter O for zero, a space, hyphen or period after the P, suffix 00): P0100 P0102 P0103 P0104, or a bare number after a code word:
   `(?<![A-Z0-9])P\s?[-.]?\s?[0O]\s?1\s?0\s?[0234](?:\s?[-:]?\s?[0O]{2})?(?![0-9])`
   `\b(?:code|codes|dtc|dtcs|error|cel|coded|fault)\W{0,6}#?\s?[0O]?10[0234]\b`
2. R2 - the mass air flow sensor in owners' words: `mass\s*[-]?\s*(?:air\s*[-]?\s*)?flow|\bmaf\b|\bm\.a\.f|air\s*[-]?\s*flow\s*(?:sensor|meter)|airflow\s*(?:sensor|meter)|air\s*mass\s*(?:sensor|meter)|\bhfm\b|air\s+meter|volume\s+air\s*[-]?\s*flow`
   together with: `check\s+engine|engine\s+light|\bcel\b|\bmil\b|\bcode|\bdtc|stall|stalled|hesitat|surg|rough|limp|reduced\s+power|jerk|misfire|lean|clean|replac|dirty|failed|bad|faulty|defect|malfunction|diagnos|sensor\s+(?:was|is)`

Background for the reader (not a sorting rule): the mass air flow (MAF) sensor sits in the intake tract between the air
filter and the throttle body and tells the engine computer how much air is coming in. P0100 is a general circuit fault;
P0102 is "circuit low input" (the signal is below the expected range, often an open circuit or a short to ground, or
very low airflow readings); P0103 is "circuit high input" (the signal is above the expected range, often a short to
voltage or a very high reading); P0104 is an intermittent circuit; P0101 is "range/performance" (the signal is
plausible but disagrees with other sensors) and is treated in a separate PulsCar article. Owners say "mass air flow
sensor", "MAF", "airflow sensor", "air meter".

For each complaint record exactly one CATEGORY and four yes/no FLAGS. You see an excerpt around the matching words
(and the whole narrative when nothing matched). Code what the excerpt supports; if it is cut off at a point that
matters, code what is stated.

## RELEVANCE
N - Not a mass air flow / airflow-sensor event on THIS vehicle. Use N when:
    - the match is false (the words appear in a list of unrelated parts or a different system; "MAF" means something else);
    - the narrative only lists the words among many other complaints, with no statement that this vehicle had a
      MAF/airflow-sensor fault, warning, code, symptom or repair;
    - the words come from another vehicle, a news story or advice, not this vehicle;
    - the MAF sensor is mentioned only as a part that was checked or replaced during a repair for something clearly
      unrelated (a transmission, brakes, a recall for another system) with no link to the MAF fault.
    NOT N (relevant) when, on this vehicle: a MAF circuit code (P0100-P0104) or P0101 is named; OR the MAF/airflow
    sensor is described as failed, dirty, replaced, cleaned, blamed, diagnosed or suspected by a shop/dealer/mechanic
    as the cause of a symptom or warning; OR a MAF code or symptom is described even if the cause is unknown.

## CATEGORY (one letter) - what was found or done, on this vehicle

S - Sensor replaced. The MAF sensor (or the MAF sensor with its housing, or the intake-air-meter assembly) was named by a shop, dealer or
    mechanic as the cause, or was replaced.
D - Dirty sensor cleaned. The sensor was cleaned (MAF cleaner, brake cleaner, a shop cleaning) and that is the
    repair stated, or a shop named dirt/oil/contamination of the sensor as the cause.
W - Wiring or connector. The MAF connector, pigtail, wiring harness, a ground, a fuse/relay or power feed to the
    sensor was named as the cause or was repaired/replaced.
A - Air path. The air filter (clogged, oiled, wrong, missing), air box, intake duct/boot/hose/clamp (cracked, loose,
    split), an intake leak after the sensor, or snow/water/debris in the intake was named as the cause or was
    repaired/replaced.
F - Software or campaign only. A reflash/recalibration, relearn/"learn" procedure, recall, TSB, special-coverage or
    warranty-extension procedure was the only repair stated (no part named as cause).
O - Another cause. A repair outside the MAF sensor and its connector/air path was named as the cause (throttle
    body, MAP/IAT sensor, PCV, fuel system, ECM, engine or transmission failure, a different system), or the code or
    symptom was traced to something else.
K - Checked and cleared. The shop or dealer inspected or tested and found no fault, or only cleared the code, with
    no repair; or the light went out by itself and nothing was done.
U - No diagnosis or repair stated. The event is reported but nothing was found or done yet, or the complaint does
    not say; also an owner's own guess, a forum, a code reader or scan with no shop/dealer/mechanic mentioned.

Precedence when more than one fits: use the FINAL repair the complaint reports as having fixed it (or, if it never
got fixed, the cause the shop named last). A part replaced that the owner says did not help does not count. If
several parts were replaced together and no single one is named, use the most specific named part in the order
W, A, D, S. Among F, O, K, U: F before O before K before U. A cause the owner merely guesses at does not count (an
owner's "probably the MAF sensor" is U unless a shop or the dealer said it, or the part was replaced by someone).

## FLAGS (yes/no)

stall - the complaint states that while driving or at a stop the engine stalled, shut off, lost power, went into
    limp/reduced power, or hesitated/surged badly because of this fault.
nostart - the complaint states the engine would not start, started hard or died soon after starting because of this fault.
recall - the complaint states that a recall, special coverage, service campaign, extension, TSB or "known issue"
    notice for this vehicle was performed, offered, missing, refused, asked about, or is blamed or credited for this event.
returned - the complaint states that after a repair or a reset the same light, code or symptom came back, or the
    repair did not fix it.

## OUTPUT

One CSV line per complaint, in the order given, no header line:
`odino,category,stall,nostart,recall,returned,note`
category is one letter (N S D W A F O K U); flags are yes or no (for N, all four flags are no);
note is at most 15 words, no commas, saying what decided the category.

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ADDENDUM FOR THE SECOND BATCH
Fingerprint of the addendum, taken before the second batch was sorted: 72b9f429d4734533af8fe91674f9b9b94913db9dec12aedf69174ab080be7877 (2026-10-14T06:04:14Z)

The first text searches missed four kinds of wording. A second, independent search added 89 complaints:
1. P0101 named with no MAF word (the first search listed only P0100, P0102, P0103, P0104 as code searches);
2. MAF words with none of the context words the first search required;
3. "mass air", "mas air", "mass flow", "MAS sensor" written without "flow";
4. owner wording such as "air flow detector", "air flow circuit sensor", "air flow codes", "MAFF".
The sorting rules above apply unchanged to these complaints (relevance N / not N, categories S D W A F O K U, flags stall nostart recall returned, and rules R1-R8 as applied in the first batch: a MAF stated as replaced is S even if it did not hold; a bare inventory of three or more other repairs is N; an owner's own inference with nothing replaced or named by a shop is U).

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RULES APPLIED TO SETTLE DISAGREEMENTS AND TO THE CONSISTENCY CHECK (each decision in the published complaints file names the rule applied)
- R1 a MAF sensor stated as REPLACED (by a shop, dealer, mechanic or the owner) is S even if the fix did not hold (returned=yes). "Told it is the MAF" counts as S only when a shop/dealer/mechanic is the one who said it; a code reader, an app, a forum or an unnamed "I was told" with nothing replaced is U.
- R2 the MAF only in a list of parts changed or checked among several unrelated ones, a preventive replacement under a service package, background about a recall for another symptom, or ruled out as fine while the real symptom is elsewhere -> N (no MAF fault is described on this vehicle).
- R3 when the narrative says the final repair that fixed it (or the cause the shop named last) was outside the MAF sensor and its connector/air path, the category is O even if the MAF was replaced first.
- R4 several parts changed together: most specific in the order W, A, D, S; a throttle body or other O part alongside does not outrank them.
- R5 a reflash/ECU update with the sensor "updated" and no part named -> F.
- R2b (tightened) a bare inventory: the MAF is one item in a list of three or more other repairs or checks with nothing singling it out (no code, no diagnosis naming it) -> N. A fix attempt that names the MAF with at most two other parts, or ties it to a code or symptom, is relevant.
- R7 two parts of the air path/filter replaced with the sensor: the order of R4 applies (an air filter or intake part replaced together with the MAF makes the category A, and the returned flag shows whether it held).
- R8 an owner's inference about the cause (water reaches the sensor, the ECM is to blame, a TSB read online) with nothing replaced or named by a shop -> U.
- R6 flags: stall = stalled, shut off, lost power, limp/reduced power or no acceleration stated as happening (plain hesitation or a slow response is not a stall); returned = the same light, code or symptom came back or the repair did not fix it.

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POOL HISTORY
- First search: 575 complaints (a MAF circuit code by any spelling: 21; the sensor in owners' words with a word about a fault: 560; the two overlap).
- Independent second search (a separate search of the same file, with no access to the sorting): about 1,150 narratives read outside the pool; 89 candidates that meet the unchanged relevance rule were added (P0101 written with no sensor word 26, "mass air" or "mas air" without "flow" 22, sensor wording with no context word 2, "air flow" owner wording 11, and others). The addendum above was fixed before they were sorted.
- Final: 664 complaints; 579 relevant, 85 not relevant. A relevant complaint is one that describes a mass air flow fault on the owner's vehicle.
- After the settling of disagreements, a consistency check moved 32 agreed rows: 16 where the sensor was stated as replaced but both sorters had put the complaint in "no diagnosis" (to S), and 16 where the sensor was one item in a bare list of three or more other repairs (to N).