SORTING RULES - VEHICLE SPEED SENSOR "A" MALFUNCTION (P0500) COMPLAINTS, WITH THE SISTER CODES P0501 P0502 P0503 AND THE SPEED-SIGNAL FAULTS AROUND THEM
PulsCar analysis of NHTSA public data, October 2026. License: CC BY 4.0

Fingerprint of the sorting rules written before sorting: 2026-10-21T14:03:23Z 45d53d4732364d57c77a7e867b5268f157e4f717516b6176af9bce1d14f9d5c9
Fingerprint of the addendum written before the second batch was sorted: 2026-10-21T14:27:51Z 969e2703265e8d14101b0140fddf69cd825bc96654a5465c90f6026d81df1e69

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PART 1. THE SORTING RULES, AS WRITTEN BEFORE ANY COMPLAINT WAS SORTED
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# Sorting rules - vehicle speed sensor "A" malfunction (P0500) complaints (P0500 study, with the sister codes P0501 P0502 P0503)

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 any of the following case-insensitive text searches. R2, R3 and R4 also need words from the "failure" list (and R3, R4 a context list) somewhere in the same narrative. The searches are deliberately strict: the loose version (any speedometer or speed-sensor mention) returns about 4,900 narratives, most of them crash accounts, brake events or lamp complaints that say nothing about a speed signal.

1. R1 - the code P0500 or a sister code (P0501 P0502 P0503) by any spelling (letter O for zero, a space, hyphen or period after the P, suffix 00), or the bare number after a code word:
   `(?<![A-Z0-9])P\s?[-.]?\s?[0O]?\s?5\s?0\s?[0-3](?:\s?[-:]?\s?[0O]{2})?(?![0-9])`
   `\b(?:code|codes|dtc|dtcs|error|cel|coded|fault)\W{0,6}#?\s?[0O]?50[0-3]\b`
2. R2 - a vehicle speed sensor in owners' words: `vehicle\s*speed\s*(?:sensor|signal)|\bvss\b|(?:transmission|trans|output|input|turbine|tail\s*shaft|tailshaft|speedometer)\s*speed\s*sensors?|speed\s*sensors?` (not when it reads "wheel speed sensor"), together with a failure word.
3. R3 - the speedometer: `speedometer|speed\s*gauge`, together with a failure word and a context word.
4. R4 - the wheel-speed side: `wheel\s*speed\s*sensor|abs\s*sensor|tone\s*ring|reluctor|exciter\s*ring`, together with a failure word and one of: speedometer, speed gauge, cruise, shift, check engine, MIL, CEL, engine light, code, DTC, limp.
   Failure words: `not\s+work|inoperative|stopped\s+work|stops\s+work|erratic|dead|zero|0 mph|fell to|drops to|bounc|jump|fluctuat|wrong|inaccurate|incorrect|no\s+reading|doesn't work/read/move/register|not\s+read/regist/mov|quit|died|fail`
   Context words (R3): `check engine|MIL|CEL|engine light|code(s)|DTC|cruise|shift|transmission|ABS|traction|stability|limp|reduced power`

Background for the reader (not a sorting rule): the engine computer needs to know how fast the car is moving. On many cars it takes that from a vehicle speed sensor on the transmission output shaft (or it calculates it from the wheel-speed sensors of the anti-lock brakes). P0500 means the computer sees no speed signal, or a signal that does not make sense. The speedometer, the cruise control and the way the automatic transmission shifts all depend on that signal, so owners usually report a dead or jumping speedometer, a cruise control that will not engage, harsh or late shifts, and a check engine light, sometimes with the ABS or traction light.

For each complaint record exactly one CATEGORY and five 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 speed-signal event on THIS vehicle. Use N when:
    - the match is false (the words appear in a list of unrelated parts, or a different system);
    - the speedometer or speed is mentioned only to state how fast the car was going in a crash, a sudden-acceleration or a brake event, with no statement that the speedometer, a speed sensor or a speed-related code failed;
    - "fail"/"not working" belongs to something else (brakes, lights, engine) and the speedometer or sensor is only named in passing;
    - a wheel-speed sensor / ABS sensor / tone ring is described only as an ABS-light or traction-control event, with no statement that the speedometer, cruise control, shifting, check engine light or a P0500-P0503 code was affected;
    - the words come from another vehicle, a news story or advice, not this vehicle;
    - a speed sensor is mentioned only as a part checked or replaced for something clearly unrelated.
    NOT N (relevant) when, on this vehicle: P0500 or a sister code (P0501-P0503) is named; OR a vehicle speed sensor / transmission output or input speed sensor is described as failed, replaced, blamed, diagnosed or suspected by a shop/dealer/mechanic; OR the speedometer is described as dead, stuck at zero, jumping, erratic or wrong (whatever the cause, including the instrument cluster); OR cruise control or shifting is described as failing together with a speed-sensor / speedometer / speed-code wording; OR an ABS wheel-speed sensor or tone ring is described as the cause of a wrong speedometer, a dead cruise control, bad shifting or a check engine light.

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

S - Speed sensor. The vehicle speed sensor, or the transmission output / input / turbine speed sensor, was named by a shop, dealer or mechanic as the cause, or was replaced and that is the repair stated.
A - Wheel-speed / ABS side. A wheel-speed sensor, tone ring (reluctor, exciter ring), wheel hub or bearing assembly carrying the sensor, or the ABS module was named as the cause or replaced and that is the repair stated.
W - Wiring or connector. A connector, pigtail, wiring harness, ground, fuse/relay or power feed (speed sensor, cluster or transmission connector, rodent damage) was named as the cause or was repaired/replaced (including a recall or special-coverage wiring repair).
C - Instrument cluster, computer or software. The instrument cluster / speedometer unit was replaced or repaired, or the engine/transmission/body computer (ECM/PCM/TCM/BCM) was replaced or reprogrammed, or a reflash / re-tune / relearn was the only repair stated (no sensor part named as cause).
T - Transmission or driveline internals. The transmission (or transfer case, differential, drive gears) was replaced, rebuilt or repaired inside, or its mechanical failure was named as the cause of the speed signal or shifting fault (not a speed sensor mounted on it, which is S).
O - Another cause. A repair outside the groups above was named as the cause (tire size or final-drive gear change, battery, alternator, engine mechanical, another sensor, 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 fault went away 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, S, A, C, T. Among O, K, U: O before K before U. A cause the owner merely guesses at does not count (an owner's "probably the speed sensor" is U unless a shop or the dealer said it, or the part was replaced by someone).

## FLAGS (yes/no)

speedo - the complaint states that the speedometer was dead, stuck at zero, jumping, erratic or wrong because of this fault.
cruise - the complaint states that the cruise control would not engage, cancelled itself or was unavailable because of this fault.
shift - the complaint states that the automatic transmission shifted wrongly (harsh, late, flaring, stuck in one gear, no upshift, limp mode) 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,speedo,cruise,shift,recall,returned,note`
category is one letter (N S A W C T O K U); flags are yes or no (for N, all five flags are no); note is at most 15 words, no commas, saying what decided the category.

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PART 2. ADDENDUM, WRITTEN AFTER THE COMPLETENESS SEARCH AND BEFORE THE SECOND BATCH WAS SORTED
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# Addendum to the sorting rules - second batch (written before any complaint of the second batch was sorted)

A completeness search of the complaint file after the first batch was sorted found complaints the first text searches missed, because the first searches required a failure word and (for the speedometer) a context word. The search found 3,549 candidates. They fall into two kinds:

1. 1,357 candidates that were each opened and judged on the full narrative against the relevance rule above. These are all added to the set and sorted exactly like the first batch. They are: speedometer failures with no context word (mostly instrument-cluster blackouts), the Ford/Lincoln 6R80 output-shaft speed sensor ("OSS") and molded lead-frame narratives, misspellings (SPEDOMETER, SPEED METER, SPEED CENSOR, MPH GAUGE), other speed-signal codes (P0715-P0723, P1500, P2159, P1722, U1412), and wheel-speed sensors tied to limp mode, cruise loss, wrong speed or shifting.
2. 2,192 candidates found by three broad searches and judged only by reading a sample: speedometer plus a failure word (907), speedometer with looser failure wording (564), and Ford/Lincoln/Mercury molded lead-frame narratives (721). A random sample of 100 of each group (seeded, seed 20261021) is added and sorted exactly like the rest; the other 1,892 are NOT sorted, are listed by number in the published file of complaints not sorted, and are never counted as part of any total in the article.

Sorting rules for this batch are the rules above, with these clarifications:
- A Ford/Lincoln molded lead-frame (the molded frame inside the transmission that carries the output speed sensor) named by a shop, dealer or mechanic as the cause or replaced is category S (it is the housing of the speed sensor). A lead-frame narrative that states no speed symptom, code or repair that touches the speed signal is N.
- The speed codes P0715-P0723, P1500, P2159, P1722 and U1412 count as speed-signal codes for the relevance rule when they are named for this vehicle.
- A narrative whose only speed-signal fact is that the whole instrument cluster or display went blank counts as a speedometer failure (flag speedo = yes) when the narrative says the speedometer or speed readout was lost.

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PART 3. RULES USED TO SETTLE DISAGREEMENTS
Each decision in the published complaints file names the rule applied in the column rule_applied. Rules R1 to R54 settled the complaints on which the two sortings differed; the rules applied in the later full-text checks are listed in the same column (R200 was written for the second pass over the complaints first sorted U). These R-numbers are separate from the labels R1 to R4 given to the four text searches in Part 1.
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- R1 an owner's, code reader's, parts-store's or forum's statement of the cause, or a repair the owner only plans, with no shop/dealer/mechanic naming or doing it -> U.
- R2 a part named as the cause by a shop, dealer or mechanic, or replaced, is the category when it is the repair stated as fixing it, or the last cause named. A part replaced that the owner says did not help does not count (precedence in the sorting rules): the category then follows what was found or done last.
- R3 a speed sensor, speedometer or wheel sensor only in a list of three or more parts changed or checked, with nothing singling it out (no code, no diagnosis naming it) -> N.
- R4 crash, sudden-acceleration, brake or ABS-light-only accounts where no speed sensor, speedometer, cruise or shifting failure and no P0500-P0503 code is stated -> N.
- R5 a shop that checks, tests or finds nothing, or says the event is a non-issue, -> K; a parts-store reading is not a shop.
- R6 flags are yes only when the excerpt states them: speedo = speedometer dead, at zero, jumping, erratic or wrong; cruise = cruise control would not engage, cancelled or unavailable; shift = wrong automatic shifting (harsh, late, flare, stuck gear, no upshift, limp mode); plain hesitation or a rough idle is none of these.
- R7 recall = yes only when a specific recall/notice/TSB/special coverage was performed, offered, seen, named, asked about or reported missing; a general remark that the maker should recall, or a plan to check later -> no.
- R8 returned = yes only when a repair, clear or reset was done and the same light, code or symptom came back, or the owner says the repair did not fix it; repeated episodes before any repair are not returned.
- R9 an instrument cluster / speedometer unit named by a shop as the cause or replaced -> C (sorting rules).
- R10 a speedometer that reads wrong only because of tire size, final-drive gearing or a computer tune the owner had changed -> O.
- R11 a code read anywhere that names a speed sensor, with no shop/dealer/mechanic saying the part is the cause and no replacement -> U.
- R12 a transmission "lead frame" (the molded frame inside the transmission that carries the output speed sensor) named by a shop/dealer/mechanic as the cause or replaced -> S (not W, which is for connectors/harness).
- R13 a shop's hedge ("may be", "assumed", "either X or Y", "suggested") or a block where no definite cause is named -> category U.
- R14 a repair/diagnosis the shop names for a different symptom than the speed fault (fuel regulator, side-warning module, ABS repair quote with no speed diagnosis) -> not the cause; category U.
- R15 text of a recall notice about a speed sensor on a vehicle that itself had no speed-signal fault -> N.
- R16 a digital display/cluster blackout that takes the speedometer out of view counts as speedometer dead (and cruise unavailable if the text says so).
- R17 a loose battery cable/terminal is a battery cause -> O.
- R18 recall = yes when a specific recall/campaign number or name (e.g. NHTSA campaign, Takata) is named for this vehicle, even if the campaign is about another system.
- R19 wheel-speed sensors, hubs or ABS parts replaced/blamed where the excerpt states no speedometer, cruise, shifting, check-engine or P0500-P0503 effect (ABS/traction lights or an unnamed failure only) -> N.
- R20 when the final category is N, every flag is no (recall included), whatever the text says.
- R21 "VSS" on a Can-Am Ryker or Spyder means the Vehicle Stability System, not a speed sensor -> N.
- R22 a valve body that houses the transmission speed sensor, named by a mechanic as needing replacement, is treated like the lead frame (R12) -> S.
- R23 a 1-2 mph difference between a digital readout and the dial is within tolerance, not a speedometer fault -> N.
- R24 speedometer or gauges going to zero or floating only as part of an engine stall, lockup or power loss, with no speed-signal wording -> N.
- R25 a different part or side failing after a repair of another part is not "returned" unless the text says the same symptom came back or the repair did not fix it.
- R26 a part named only by the maker's campaign statement or by the owner, with no shop/dealer/mechanic diagnosing this vehicle -> U.
- R27 a transmission shift solenoid named by a mechanic as failed -> T (transmission internals).
- R30 a recall performed on a speed sensor, with no statement that the part was replaced or what the outcome was -> category U.
- R31 an owner's question or guess that a non-speed code (e.g. P0700) relates to a speed sensor, with no P0500-P0503/P072x code and no shop naming the sensor -> N.
- R32 a shop/dealer/service advisor saying the fault is a "known issue" of the vehicle line counts as recall=yes (sorting rules, "known issue" notice); an owner's own "known issue" remark -> recall no.
- R33 a restart/key-cycle that only temporarily clears the symptom is a reset, not a shop finding -> category U (not K).
- R34 a valve body with the TCM built in, named as the cause or as the part to replace -> T (transmission internals).
- R35 a driveline speed sensor that is neither the vehicle speed sensor, a transmission sensor nor a wheel sensor (half shaft, driveshaft, differential, transfer case, motor) -> O when a speed-signal symptom is stated; N when the account is only an ABS/traction/4WD fault.
- R36 transmission slip / loss of acceleration where the speedometer only follows engine speed, with no speed sensor, code or speedometer-fault statement -> N.
- R40 a speedometer/instrument-panel illumination (backlight) failure where the speed readout itself is not stated lost or wrong -> N.
- R41 coolant / transmission-fluid cross-contamination (radiator or cooler leak) named by a dealer as the cause -> O.
- R42 a speedometer that only flashes or flickers as a side effect of a key or other-system warning, with no lost or wrong reading -> N.
- R43 a speedometer showing the correct speed in the wrong unit (km/h vs mph) is a display-setting fault, not a speed fault -> N.
- R44 a lead-frame narrative (addendum) that states no speed symptom, code or repair touching the speed signal -> N.
- R50 recall = yes also when the text says the owner/dealer looked for a recall or bulletin for this fault and none exists or the VIN is not covered (a check with that result); a bare "why is there no recall" or "should be recalled" -> no.
- R51 routine maintenance (e.g. a transmission flush at a service interval) done before the fault is not a repair of it -> returned no.
- R53 a speedometer that shows zero or rounds at crawling speed, or whose needle stops at crash impact, is not a speed-signal fault -> N.
- R54 gear-change, downshift, no-start or range-sensor narratives (lead frame mentioned or not) that state no speedometer, speed sensor or speed-signal code, and no speed-sensor repair -> N (addendum, lead-frame rule).
- R200 a crankshaft/engine reluctor or tone wheel (engine RPM, magnetic strip recall) is not a vehicle-speed signal -> N.
- R300 a molded lead frame (the Ford transmission frame that carries the output speed sensor) named as the cause or replaced by a dealer or mechanic is category S (addendum, R12) - applied to the first-batch rows that were sorted before the addendum existed and had been put under W or T.

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PART 4. POOL HISTORY
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- First searches: 2,256 complaints (a code spelling, a vehicle speed sensor in owners' words, the speedometer together with a failure word and a context word, or the wheel-speed side together with a failure word and a speed-related word).
- Completeness search (a separate search of the same file, run after the first batch was sorted): 3,549 candidates. 1,357 were each read individually on the full text and added; 2,192 were found by three broad searches (speedometer plus a failure word 907; speedometer with looser failure wording 564; Ford, Lincoln and Mercury lead-frame complaints 721), of which a seeded random 100 from each group (300 in all) were added and sorted like the rest. The other 1,892 were not sorted; they are listed by number in p0500-complaints-not-sorted.txt and are in no total.
- Pool after the merge: 3,913 complaints (first search 2,256, second search read one by one 1,357, second search random samples 300).
- Every complaint was sorted twice, independently, by the written rules; disagreements (480 complaints, on at least one field) were settled by the rules above.
- Second full-text pass over every complaint first sorted U (2,213 complaints): 255 changed category (to a named cause, to checked-and-cleared, or to not a speed-signal fault).
- Consistency step (rule R300): 59 complaints in which a dealer or mechanic named the Ford molded lead frame as the cause had been put under wiring or transmission before the lead-frame rule was written; they were moved to speed sensor (S).
- Full-text check of the recall, returned, shift and cruise flags (1,398 complaints whose wording pointed to such an event): 570 changes to flags. Altogether 736 complaints were changed by the two full-text checks (resolution column: "changed in full-text check").
- Final: 3,913 complaints; 3,384 relevant (a speed-signal event on the owner's vehicle), 529 not relevant (N). Categories among all 3,913: U 1,958, S 483, A 274, C 211, K 195, W 73, T 91, O 99, N 529.
- Flags among all 3,913: speedometer 2,510, cruise control 203, shifting 1,254, recall 1,113, problem returned 573.