PULSCAR ANALYSIS - P0606 (CONTROL MODULE PROCESSOR) AND ENGINE / POWERTRAIN CONTROL MODULE FAULTS - THE SORTING RULES
PulsCar analysis of NHTSA public data, October 2026. License: CC BY 4.0

Fingerprints (date UTC and checksum of each file below, taken before any complaint was sorted under it):
2026-10-14T08:29:24Z
92ec86e6f45de2c8f5743f81dab490202fe6578c556cf238934748b0a34f5225  sorting-rules.md
2026-10-14T09:09:37Z
aa8875289e508101f97b5e75ef2058d7e883872541c3eb7bf6b35fa20bb38bbb  sorting-rules-addendum.md
2026-10-14T15:36:37Z
0edc7833bce6d4987885ee32d612a0e24d310a84613c64a8c21528d165fcf49f  sorting-rules-addendum-2.md

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PART 1 - THE SORTING RULES (fixed before the first batch of 926 complaints was sorted)
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# Sorting rules - engine / powertrain control module (ECM / PCM) processor fault complaints (P0606 study)

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:

1. R1 - a control-module internal code by any spelling (letter O for zero, a space, hyphen or period after the P, suffix 00): P0601 P0602 P0603 P0604 P0605 P0606 P0607, or a bare number after a code word:
   `(?<![A-Z0-9])P\s?[-.]?\s?[0O]\s?6\s?0\s?[1-7](?:\s?[-:]?\s?[0O]{2})?(?![0-9])`
   `\b(?:code|codes|dtc|dtcs|error|cel|coded|fault)\W{0,6}#?\s?[0O]?60[1-7]\b`
2. R2 - the engine/powertrain control module named in owners' words within about 50 characters of failure wording (fail, defective, bad, faulty, internal, malfunction, processor, corrupt, fried, dead, shorted, burn), and the same narrative also mentions a check-engine light, a code, a stall, a no-start or limp/reduced power:
   module words: `\becm\b|\bpcm\b|\becu\b|\bm\.?c\.?u\b|engine\s+control\s+(?:module|unit|computer)|powertrain\s+control\s+(?:module|unit)|engine\s+(?:computer|management\s+computer|management\s+module)|engine\s+brain|main\s+computer|control\s+module\s+processor|\bde[mc]\b(?=\W)|motor\s+control\s+unit`
   failure words: `fail|defect|\bbad\b|faulty|internal|malfunction|processor|corrupt|fried|\bdead\b|shorted|burn`
   context words: `check\s+engine|engine\s+light|\bcel\b|\bmil\b|\bcode|\bdtc|stall|no[- ]start|won.?t\s+start|wouldn.?t\s+start|limp|reduced\s+power`

Background for the reader (not a sorting rule): the engine control module (ECM) or powertrain control module (PCM) is the
computer that runs the engine. P0606 is "control module processor": the module's own self-test found a fault in its
main processor, or the two processors disagree. P0601 is a memory checksum error, P0602 a programming error, P0603 a
keep-alive-memory error, P0604 a RAM error, P0605 a ROM error, P0607 a performance fault. Owners say "ECM", "PCM",
"ECU", "engine computer", "engine control module", "engine brain".

For each complaint record exactly one CATEGORY and four yes/no FLAGS. You see an excerpt around the matching words
(and the first part of the 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 an engine / powertrain control module event on THIS vehicle. Use N when:
    - the match is false (the words appear in a list of unrelated parts or another system; "ECM" or "PCM" means something else);
    - the module in question is clearly NOT the engine/powertrain module: transmission control module (TCM), body control
      module (BCM), ABS module, airbag module, infotainment, TIPM/fuse box, hybrid battery or charging controller, a
      steering or brake module - unless the complaint also says the engine/powertrain module (or P0601-P0607) was involved;
    - the narrative only lists the words among many other complaints with no statement that this vehicle's engine/powertrain
      module had a fault, warning, code, symptom or repair;
    - the words come from another vehicle, a news story or advice, not this vehicle;
    - the module 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 a module fault;
    - "failed" is about another part and the module is only the place where a code was read.
    NOT N (relevant) when, on this vehicle: a code P0601-P0607 is named; OR the engine/powertrain module is described as
    failed, faulty, replaced, reprogrammed, blamed, diagnosed or suspected by a shop/dealer/mechanic as the cause of a symptom
    or warning; OR a module fault symptom is described even if the cause is unknown.

## CATEGORY (one letter) - what was found or done, on this vehicle
M - Module replaced. The engine/powertrain control module (ECM / PCM / ECU) was named by a shop, dealer or mechanic as
    the cause or was replaced (new, remanufactured or used).
F - Software or campaign only. A reflash/reprogram/software update, "learn" procedure, recall, TSB, special-coverage or
    warranty-extension procedure was the only repair stated (no part named as cause).
W - Power, ground or wiring. Battery, battery cable or terminal, alternator/charging, a ground strap, a fuse or relay or
    power feed to the module, a connector, pin or wiring harness at the module was named as the cause or was repaired/replaced.
L - Liquid or corrosion. Water, moisture, coolant, oil or corrosion inside the module or its connector was named as
    the cause (the module or connector was then replaced, dried or cleaned).
O - Another cause. A repair outside the module and its power/wiring was named as the cause (a sensor, injector, engine,
    transmission, 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 things
were done together and no single one is named, use the most specific named cause in the order L, W, M. 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 computer" 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 M F W L 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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PART 2 - ADDENDUM FOR THE SECOND BATCH (fixed before the 1,199 second-search complaints were sorted)
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# Addendum to the sorting rules - second search (written before any second-search complaint was sorted)

An independent check of the complaint file after the first sort found complaints the first text search had missed. Reasons: the first search knew only the one-word spelling "powertrain control module" (not "power train control module", which many complaints use), the generic names "engine computer", "main computer", "engine module", "electronic control module" and "DME", the letter-O spelling of codes, code forms with a suffix (P060194), and the internal-module family codes P060A, P060B, P060C, P061A-P061E and P062F; it also required the failure word and the context word together.

Added to the pool (second search): every complaint found by the check in which the module is named as failed, faulty, diagnosed, coded, damaged, water-damaged, not communicating, or named as the problem of a recall or campaign on this vehicle, under any of the spellings above, or in which a P0601-P0607 / P060A-C / P061A-E / P062F code is named.

NOT added (scope rule, applied before sorting): complaints that name the module only as replaced, updated, reprogrammed or flashed, with no failure wording near it. They answer a different question (what an update or replacement cost) and were left out of the sorted set. The check found 2,530 of them. (This scope rule was reversed on 14 October 2026: those complaints were then sorted too; see Part 2B.)

The sorting rules above (relevance, categories M F W L O K U, flags, precedence) and the decision rules R1-R26 apply unchanged to the second-search complaints.


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PART 2B - ADDENDUM 2 FOR THE THIRD BATCH (fixed before the 2,530 complaints that only mention a replaced or updated module were sorted)
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# Addendum 2 to the sorting rules - the complaints that only mention a replaced or updated module (dated 2026-10-14; written before any of them was sorted)

The first addendum left out 2,530 complaints in which the engine/powertrain control module is named only as
replaced, updated, reprogrammed or flashed, with no failure wording near it. That scope decision is reversed:
all 2,530 are now sorted, twice, independently, under the sorting rules above and added to the same set. Nothing in the
relevance rule, the categories (M F W L O K U), the flags or the precedence order changes, and no new category is added.

How these complaints are sorted (this is the existing rule applied to wording that was held back, not a new rule):

- Relevance. A complaint that says a shop, dealer or mechanic replaced the engine/powertrain module (or named it as the
  cause), or reprogrammed/updated it as the repair for a symptom, warning or code on this vehicle is relevant: M for a
  replacement or a named module cause, F for a reflash, update or reset that is the only repair stated.
- A complaint in which the module is replaced or updated only as one step inside a repair for something clearly
  unrelated (a transmission, brakes, an airbag, a recall for another system), with no module fault, code or
  module-caused symptom stated, is N.
- A routine "software update" or "flash" the dealer did during another visit, or one that is part of a campaign for
  another defect, with no module fault or symptom stated, is N. An owner who says the update was the fix for a stall,
  no-start, light or code is relevant (F).
- A module named as replaced or updated, where the narrative is cut off before it says why, is sorted on what is
  stated: replaced by a shop or dealer is M; updated is F; nothing else stated is U only if a symptom of the module is
  described, otherwise N.
- The flags (stall, nostart, recall, returned) are read from the text exactly as defined above; a flag stays "no" when
  the excerpt does not state it. For N all flags are no.

Counts are made on the whole set afterwards: the held-back complaints change every share that depends on the size of
the set, and the published tables show the first search, the second search and these complaints together.


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PART 3 - THE RULES USED TO SETTLE DISAGREEMENTS
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Every complaint on which the two independent sortings differed (category or any flag) was read and settled under one of these written rules; the rule applied is in the rule_applied column of the complaints file. 168 disagreements in the first batch (rules R1 to R26) 254 in the second (rules R1 to R33) and 652 in the third (rules R1 to R34; one decided directly by addendum 2). At the last check rule R35 was added (below); it narrows R5 and the second clause of R27.

First batch:
R1 recall=yes when the narrative names a recall, campaign, TSB, service bulletin, extension or special coverage for this vehicle (performed, offered, missing, VIN excluded, asked about) or the owner asks for / complains about a missing recall ("should be recalled", "chose not to recall"); no for generic "the manufacturer knew" with no such word, for an investigation alone, and for a plain dealer "update" not called a recall/campaign/TSB.
R2 returned=yes only when a repair, part replacement, reflash, reset or code clearing is stated and the same light/code/symptom comes back or the fix did not work; recurrence with no repair stated (not repaired, could not replicate, a plain restart) is returned=no.
R3 stall=yes only when the text states that the engine stalled, shut off, lost power, went into limp/reduced power, or hesitated/surged/stumbled badly on this vehicle; hypotheticals ("may cause", "could have"), "failed to accelerate" alone, a deliberate shut-off, a transmission-only gear problem, a restart implied by cut-off text, or excerpt cut before the event are stall=no.
R4 a fix that a shop/dealer says is needed or advised but not yet done counts as the stated repair or named cause (module -> M, software reflash -> F), as does a transmission/other shop naming the ECM as the real problem.
R5 a repair or replacement that the narrative says did not fix the problem does not count; the category falls to the last cause/finding that does count (named other cause -> O, nothing found -> K, otherwise U); an owner-only guess left over is U.
R6 when a shop/dealer suspected or tested the engine module and then cleared it in favour of another module or part (TIPM, fuse box), the complaint stays relevant and the category is O.
R7 the module named only as one item in a list of many systems, codes or possible causes, or as an owner's side hypothesis ("or a faulty ECM"), or only as something the owner reset or a fee line, with no code P0601-P0607, no shop diagnosis and no symptom specific to it -> N; an owner or relayed assertion that this vehicle's PCM/ECM is bad (no shop) -> U.
R8 when a shop names several causes, an unhedged one beats a hedged one ("potential", "may"), and among equally named causes use the sorting-rules order L, W, M (L when corrosion/liquid is itself found at the module wiring).
R9 a dealer or shop that looked and found no code / could not diagnose or duplicate, or only cleared codes (even a dealer salesman), with no repair -> K; an owner-only report or code reader -> U.
R10 oil or liquid merely noted on the module/harness while the shop names a different part as the cause is O, not L; L needs the liquid or corrosion to be the stated cause or finding.
R11 "ECU sensor" or "PCU sensor" named by a dealer without saying the module failed is a sensor cause -> O, not M.
R12 the ECM/PCM appearing only as the place where a code was read or as a label inside another system's diagnosis (VSA/ABS/CAN U-codes, transmission, crank/reluctor, O2, valve-body or vacuum-pump codes, hybrid propulsion codes), with another part blamed and the module not accused -> N.
R13 nostart=yes when the text states it would not start/restart, hard-start, needed several attempts, or died right after starting; a dead battery or "dead" alone, or an attempt only to jump-start, is no unless start failure is stated (an attempted start in the repair narrative that fails counts).
R14 pasted recall/TSB wording describing a defect in general, with no statement about the complainant's own vehicle having the fault, code, symptom or repair -> N; if the owner says the own car has the recall's problem it is relevant (U unless a repair is stated).
R15 a diagnosis worded only as "no connection/communication" for the PCM, without naming wiring, connector or power feed, is not W; with nothing repaired it is U.
R16 a module that is not the engine/powertrain module (steering/EPS ECU, hybrid battery or EV motor controller, mechatronic unit, brake/chassis C-codes) is N even if the word ECU/ECM is used.
R17 an ECU/PCM update (or missing update) that is merely part of a campaign or TSB for another defect, with no module fault or module-caused symptom stated, -> N; when the owner blames the module or its software, or the update is the stated remedy for a code/symptom on this vehicle, it is relevant (F / recall=yes).
R18 when returned=yes follows a campaign reflash that is the only repair, the category is F, not U.
R19 (not used; merged into R12).
R20 no shop/dealer/mechanic named as the source of the diagnosis (owner research, owner linking, "find out it's the PCM") -> U, not M or O.
R21 a shop/dealer/mechanic who names the ECM/PCM as probably or possibly defective, or names it among causes of damage, counts as naming it -> M even if not replaced; an owner-only claim does not.
R22 failures described for other owners' vehicles (not this vehicle's own event) do not make the complaint relevant -> N.
R23 when shops name different causes at different times, the last-named cause or last repair that fixed it controls the category.
R24 a campaign reflash or recall done BEFORE the problem appeared is not a repair for it: the category is then the later named cause (O) or U if nothing is named; it is not F; returned=yes if the same light/CEL appears again after a following repair.
R25 when the only repair stated is a replaced non-module part (battery) and the module failure is stated by the owner without a named source, the replaced part sets the category (W).
R26 a parts-store scan or free test (AutoZone) or a bare code reading without a shop diagnosis is a code reader -> U; it is not M or W.

Second batch (new rules R27 to R33; R1 to R26 apply unchanged):
R27 when two or more repairs are stated for the same problem (part replaced, reflash, recall remedy, reset) and every one of them is said to have failed, with no separate cause named by a shop, the category is U; a lone module replacement that did not help is also U (R5).
R28 when a shop or the owner's account says the engine/powertrain module itself burned, failed or was damaged and another part (O2 sensor, timing chain, coils) is only the upstream reason for the damage, the module's failure/replacement sets the category M, not O.
R29 a wiring harness that is not stated to connect to the engine/powertrain module (engine, injector, transmission lead-frame harness) is a part outside the module: category O, not W; W needs the connector, pin or harness at the module itself.
R30 an engine failure or seizure for which no cause is named, where the only link to the module is a missing/unperformed ECU upgrade campaign or the maker refusing coverage because of it, is U with recall=yes (not O, not F).
R31 a violent shudder, jerk or stumble while driving counts as stall=yes under R3 (stumbled badly); a rough idle, a noise or "unable to accelerate" alone does not.
R32 a dealer "reset" of the PCM/ECM described as a repair attempt (not just clearing stored codes) is a reset/relearn procedure and counts as F; clearing stored codes only is K.
R33 when a reflash/reset and a non-module part are done together in one repair and nothing says either failed, the sorting-rules order F before O decides: F.

Third batch (new rule R34; R1 to R33 apply unchanged; a rule_applied of "addendum 2" means the complaint was decided directly by addendum 2):
R34 an ECM/PCM update done under a manufacturer settlement or emissions-modification program counts as a campaign for recall=yes only when the narrative itself calls it a settlement program, campaign, recall or TSB; a plain "update" or "emission modification" with no such word is recall=no.

R35 (written down on 14 October 2026, at the last check): a single stated repair, replacement or reflash that did not fix the problem keeps that repair's category (M, F, W or O) and returned=yes records the failure; R5 and the second clause of R27 send a complaint to U only when two or more repairs all failed with no cause attributed by a shop, or when no repair or cause is attributed at all. The last check applied R35 to the complaints it re-sorted; about 100 complaints settled earlier under R5 or R27 (category U, returned=yes) were not all re-sorted under it and may sit in U although they state one failed repair.


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PART 4 - HOW THE POOL GREW
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First search: 926 complaints (61 name a code P0601-P0607 by a spelling the first search knew; 874 name an engine or powertrain control module near a word of failure and also a check-engine, code, stall, no-start or limp word; 9 do both). Category agreement between the two independent sortings: 834 of 926 (90.1%).
Independent second search: 3,729 complaints proposed. 1,199 that name the module as failed, faulty, diagnosed, coded, damaged, not communicating or the problem of a recall, or name a P060x/P061x/P062F code, were added and sorted by the same rules (category agreement 1,078 of 1,199, 89.9%). 2,530 that name an engine computer only as replaced, updated or reprogrammed with no word of failure near it were first left out (scope rule in Part 2).
Third batch (14 October 2026): the 2,530 held-back complaints were sorted by the same rules, twice, independently, under addendum 2 (Part 2B), fixed before they were sorted. Category agreement in this batch: 2,139 of 2,530 (84.5%). Over all 4,655 the two sortings agree on the category in 4,051 (87.0%).
Last check: after the disagreements were settled, every complaint was checked again against its full text under these rules and the rules of Part 3; it corrected 773 complaints (289 main categories and a number of stall, nostart, recall and returned flags). Reading used in the last check (rule R35): when a stated repair, replacement or reflash did not fix the problem and no other cause is named, the complaint keeps the category of that repair and the returned flag records the failure; about 100 complaints settled earlier under R5 or R27 were not all re-sorted under it.
Result over all 4,655: 4,032 describe a control-module fault on the owner's car (M 1,189, U 949, F 828, O 591, W 297, K 90, L 88); 623 do not.