SORTING RULES - EGR (EXHAUST GAS RECIRCULATION) COMPLAINTS (P0404 AND SISTER CODES)
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: 3c72b4e1d49805dd5981b2d230df9147047afc81b16e48a91b26e03c4a95cbfd (2026-10-21T14:00:47Z)
Fingerprint of the addendum for the second batch, taken before that batch was sorted: efa971454564c447bd20dc2310158ec099ab1c810f721a79114f58452320c88d (2026-10-21T14:28:36Z)

# Sorting rules - EGR valve / EGR circuit complaints (P0404 study; sister codes P0400 to P0409 sorted with it)

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:

1. R1 - the code P0404, P0405, P0406, P0407, P0408 or P0409 by any spelling (letter O for zero, a space, hyphen or period after the P, suffix 00), or a bare number after a code word:
   `(?<![A-Z0-9])P\s?[-.]?\s?[0O]\s?4\s?0\s?[4-9](?:\s?[-:]?\s?[0O]{2})?(?![0-9])`
   `\b(?:code|codes|dtc|dtcs|error|cel|coded|fault)\W{0,6}#?\s?[0O]?40[4-9]\b`
2. R1s - a sister code of the same system (P0400, P0401, P0402, P0403), same spellings:
   `(?<![A-Z0-9])P\s?[-.]?\s?[0O]\s?4\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]?40[0-3]\b`
3. R1x - a maker-specific EGR code: P0487, P0488, P0489, P0490, P1403, P1404, P1406, P1408, P2412, P2413, P2414, P2415.
4. R2 - the words EGR or exhaust gas recirculation anywhere in the narrative (the abbreviation "e.g." is not counted):
   `(?<![A-Za-z.])e\.?g\.?r\.?(?![A-Za-z])|exhaust\s+gas\s+recirc`

Every narrative that matches any search goes to the sorters. Nothing is sampled.

Background for the reader (not a sorting rule): the exhaust gas recirculation (EGR) valve lets a measured amount of exhaust
back into the intake to cool combustion. Most valves are opened by a motor or a solenoid and report their position back
to the engine computer. P0404 is "range/performance" (the valve position the computer asked for and the position the
sensor reports do not agree); P0405 and P0406 are the position sensor circuit low and high; P0403 is the valve control
circuit; P0401 is insufficient flow and P0402 excessive flow. Owners say "EGR valve", "EGR sensor", "EGR delete",
"EGR cooler", "EGR tube", "carbon", "stuck".

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 an EGR event on THIS vehicle. Use N when:
    - the match is false (the words appear in a list of unrelated parts or in another system; "EGR" means something else);
    - the narrative only lists EGR among many other parts, with no statement that this vehicle had an EGR fault, warning,
      code, symptom, recall repair or EGR part replaced;
    - the words come from another vehicle, a news story or advice, not this vehicle;
    - the EGR is mentioned only as a part that was checked or replaced during a repair for something clearly unrelated with
      no link to the complaint (and the owner does not say EGR was a cause or suspect).
    NOT N (relevant) when, on this vehicle: an EGR code (P0400 to P0409 or a maker-specific EGR code) is named; OR the
    EGR valve, position sensor, tube, cooler, passage or pressure sensor is described as failed, clogged, replaced, blamed,
    diagnosed or suspected by a shop/dealer/mechanic as a cause of a symptom or warning; OR an EGR recall/campaign
    repair is described; OR an EGR symptom or code is described even if the cause is unknown.

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

V - EGR valve replaced. The EGR valve (with its motor/actuator, or the valve with its built-in position sensor) was named
    by a shop, dealer or mechanic as the cause, or was replaced.
C - Carbon or blockage. Carbon, soot or a plugged EGR passage, tube or port was named as the cause, or the valve/passage
    was cleaned (or a stuck valve freed) and that is the repair stated.
P - Position or EGR sensor. The EGR valve position sensor, the DPFE/differential pressure sensor, the EGR temperature
    sensor or another EGR sensor was named as the cause or was replaced on its own (not as part of a valve assembly).
W - Wiring or connector. The EGR connector, pigtail, wiring harness, a ground, a fuse/relay or the power feed to the valve
    or sensor was named as the cause or was repaired/replaced.
L - Cooler or leak. The EGR cooler (heat exchanger) was named as the cause, or coolant loss, white smoke, overheating or
    a fire/burning was tied to the EGR cooler or an EGR tube; or the cooler was replaced.
F - Software or campaign only. A reflash/recalibration, relearn 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 EGR valve, its sensors, its connector, the passage and the cooler was named as
    the cause (turbo, DPF, injector, fuel, vacuum or intake leak, ECM, engine or transmission failure, a different system),
    or an EGR delete/block was installed, 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, C, P, V, L. 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 EGR valve" 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, idled roughly or surged/hesitated 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 V C P W L 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.


## Pool history (addendum, written before the second batch was sorted)
After the first batch of 1,100 was sorted, a separate search of the complaint file for narratives the first searches missed
(owner spellings such as "ERG", "AGR", a hyphen in "re-circulation", the EGR sensor called DPFE, and narratives that name
only a recall number of an EGR campaign) found 290 more. They were sorted under the same rules in a second batch.

## Recall numbers that are EGR campaigns (second batch only, written before the second batch was sorted)
Some owners write only the number of a federal recall campaign and never the letters EGR. The recall records name the
exhaust gas recirculation (EGR) valve, cooler or module in these campaigns, so a narrative that cites one of them for
THIS vehicle counts as an EGR event (relevance rule: an EGR recall repair is described, offered, missing or performed):
  18V755 (BMW diesel, EGR cooler), 21V907 (BMW diesel, EGR cooler), 22V614 and 24V588 (BMW 540d, EGR module),
  25V700 (BMW 328d, EGR), 19V757 and VB1 (Ram 1500 EcoDiesel, EGR cooler), 20V699 and W79 (Jeep Grand Cherokee EcoDiesel,
  EGR cooler), 22V284 (Jeep/Dodge 3.6L, EGR valve), 24V308 (Hyundai Elantra/Venue/Kona, EGR valve), 26V122 (Ford, EGR valve),
  Ford customer-satisfaction programs 21M03 and 21M04 (EGR cooler).
Campaign numbers that are NOT EGR: 20V475 (crankshaft position sensor), 22V406 (fuel pump), 19V347, and any other number.
Use the same categories: a vehicle that only has the open recall, with no failure and no repair, is U with recall = yes.


## Rules used to settle disagreements and in the consistency check (R1 to R12, written while the first batch was settled; applied to every batch)
# Lead decisions on every sorter disagreement. Rules (published in the sorting rules):
R1  An EGR valve stated as REPLACED (by a shop, dealer, mechanic or the owner) is V even if the fix did not hold (returned=yes). "Told it needs replacing" counts as V only when a shop/dealer/mechanic said it and no later shop/dealer found no fault; a code reader, an app, a forum or an unnamed "I was told" with nothing replaced is U.
R1b A shop/dealer that tested and found no fault or no codes after an earlier shop's EGR suggestion that was not carried out -> K.
R2  EGR only in a list of parts changed or checked among several unrelated ones, or ruled out while the real symptom is elsewhere -> N. A bare inventory: EGR is one item in a single clause listing three or more OTHER repairs or checks, with nothing singling it out (no EGR code, no EGR diagnosis, no EGR warning) -> N. A fix attempt that names the EGR with at most two other parts, or ties it to a code, warning light or symptom, is relevant.
R3  When the narrative says the final repair that fixed it (or the cause the shop named last) was outside the EGR valve, sensor, wiring, passage and cooler, the category is O even if the EGR valve was replaced first.
R4  Several EGR parts changed together with no single one named: the most specific in the order W, C, P, V, L. An "EGR system" replaced with the valve not named = V. A valve replaced together with cleaning or gaskets = V.
R5  A reflash, recall, TSB or warranty-extension procedure with no part named -> F. If the owner then says a different cause was found, O.
R6  Flags: stall = stalled, shut off, lost power, limp/reduced power, rough idle or surging stated as happening because of the fault (plain slow response or sluggishness is not a stall; a stall blamed on another part is not this fault); returned = the same light, code or symptom came back or the repair did not fix it; recall = a recall/TSB/special coverage/warranty enhancement/known-issue notice for this vehicle is mentioned as performed, offered, refused or asked about (a statement that there is none is no).
R7  An owner's inference or a forum suggestion about the cause with nothing replaced and no shop naming it -> U. An owner's own direct finding stated as fact (opened the part and found the EGR valve/motor stuck, clogged, melted) counts as naming the cause.
R8  A P040x code string whose narrative describes another system (for example "P0402 catalytic converter") with no EGR statement -> N.
R9  Motorcycles, powersports, motorhome chassis, buses and Class 7-8 trucks and tractors (International ProStar, Mack, Freightliner Cascadia and similar) are outside this car and pickup study -> N.
R10 A sensor on the EGR cooler or an EGR temperature or pressure sensor named as the cause -> P; the cooler itself, a cooler leak or coolant loss/fire tied to it -> L; an EGR tube or pipe leak or loose joint -> O unless carbon/blockage (C).
R11 A complaint that only says a recall or campaign is open and the remedy or part is not available (or is delayed), with no failure on this vehicle described and nothing repaired -> U, recall yes. A recall letter on a vehicle with a stated symptom is still U (no cause named by a shop).
R12 A part replaced in a long run of other repairs where EGR is not singled out is N under R2, even when the narrative also says EGR; a final failure of a different part (engine, turbo) named after an EGR-cooler repair -> O under R3.


Pool history: first batch 1,100 complaints (R1 code P0404 to P0409: 15; R1s sister code P0400 to P0403: 55; R1x maker EGR code: 6; R2 the words EGR or exhaust gas recirculation: 1,068; some matched more than one search). Second batch 290 complaints added by an independent search of the whole file (owner spellings such as ERG, AGR and re-circulation, the EGR sensor called DPFE, and narratives that only cite the number of an EGR recall). Total 1,390.