CODEBOOK AND SORTING RULES - COOLANT FLUSH COMPLAINTS
PulsCar analysis of NHTSA public data, November 2026. License: CC BY 4.0

Rules dated and fixed before any complaint was sorted:
2026-11-04T08:25:30Z
d8a178418a54535b6dae759b0996e58e4eeccc2b8638e40874bad761a1865983  codebook (below)

# Codebook — coolant-flush-cost (complaints that mention a coolant service)
Pool rule (written before sorting): every NHTSA complaint received 2015-01-01 to 2026-10-04 whose text, by a phrase search, contains: "flush" within 3 words of coolant/antifreeze/cooling system/radiator fluid; "coolant/antifreeze/cooling system" followed by change/exchange/service/replacement/interval/maintenance; change/exchange/replace/drain/service + (the|my|all|old|new) + coolant/antifreeze (not followed by reservoir, hose, pump, line, sensor, tank, bottle, cap, temp, level); drain-and-fill / flush-and-fill; "wrong coolant", "incorrect coolant", coolant type, coolant incompatible/gel. Narratives with only radiator, pump, hose or thermostat replacement are not in the pool.

## Question the article asks
What did the owner say about a coolant flush, drain-and-fill or coolant change on THIS vehicle: was it routine, sold with something else, done as a fix, did it find something, did a problem start after it, or was the wrong coolant involved?

## CATEGORY (one letter; precedence M > P > D > F > S > U > R > N)
M  Wrong, mixed or incompatible coolant is named as a problem on this vehicle (wrong type put in, types mixed, gelled, "universal" coolant).
P  A problem started or got worse AFTER a coolant flush/change/drain-and-fill that the text says was done on this vehicle (heater stopped, leak, overheating, plugged core, failed part, stalled), whether or not the owner blames the flush.
D  A coolant flush/change was done (or paid for) as the remedy for a stated fault (overheating, noise, heater, code, temperature gauge) and nothing is said about trouble after it.
F  A coolant service visit or the draining of coolant FOUND a fault or bad fluid: rust, sludge, oil, milky coolant, transmission fluid in coolant, metal bits, low level, a leak, a cracked part. The flush itself is not blamed.
S  A shop/dealer RECOMMENDED, quoted or tried to sell a coolant flush/service (with or without a price), whether the owner accepted it or not, and the text does not fit M, P, D or F.
U  Owner mentions the coolant service only as part of a bigger story whose fault is something else (an unrelated recall, accident, another defect found during a visit for a flush).
R  Routine/scheduled coolant flush or change mentioned as done, due or skipped (maintenance record, interval, "I had the coolant flushed at 60,000 miles") with no problem tied to it.
N  Not about this vehicle's coolant service: another person's car, a different fluid (brake, transmission, power steering) being flushed, "coolant" only inside a recall text pasted in, radiator or pump replaced with no coolant service said, A/C, or the match is a false hit.
Precedence note: if the text says a problem began after a flush, it is P even if the flush also found something (F) or was recommended by a shop (S).

## FLAGS (yes/no; N rows get no)
amount  = the text states a dollar figure for a coolant service, flush or change (not for a whole repair). 
covered = the maker, dealer or warranty paid or offered to pay for the coolant work, or it was free.
shop_pushed = the owner says a shop or dealer recommended/pushed the coolant flush (including a visit for something else).
returned = the same symptom came back after the coolant work.

## Output format, one line per complaint
odino,category,amount,covered,shop_pushed,returned,note
(note: at most 12 words, no commas)

ADDENDUM (written after the second search, dated before the added complaints were sorted)
2026-11-04T09:01:16Z
414515c6e553240bfa126094d54d3b18fc77285754d97f74698f19e318fcec12  addendum (below)

# Addendum to codebook.md (written after the completeness audit, before sorting the added complaints)
The audit found that the first phrase search matched "flush" but missed "flushed", "flushing" and similar forms. The added complaints use the same pool rule with those forms included, plus: "cooling system service", "radiator service", "coolant fluid exchange", misspellings (collant, coolent, anti freeze), and a flush of the heater circuit/heater core.
Same CATEGORIES and FLAGS as codebook.md, with these clarifications for the added complaints:
- A flush of the heater core / heater circuit / cooling lines counts as a coolant flush (it is the coolant circuit).
- "Flush the engine" or "engine flush" counts as a coolant service only if the text ties it to coolant, antifreeze or the cooling system; an oil-side engine flush is N.
- Bleeding/burping the cooling system or topping up with new coolant, with no flush/change/drain-and-fill, is N.
- A flush only quoted in a list of repairs is S; a flush done as one step of a larger repair after fluids mixed is F (see RULES.md R2); a flush done as the remedy for a stated fault is D.
Output format unchanged: odino,category,amount,covered,shop_pushed,returned,note

RULES USED TO SETTLE DIFFERENCES BETWEEN THE TWO SORTINGS
Rules used to settle the 21 category disagreements (written after reading each in full; apply literally)
R1 A coolant formulation named as the cause of damage (new coolant reacting with hose lining, sludge or crystals from a named coolant type) counts as M, as both sorters already coded the crystallizing-coolant complaints.
R2 When a fault was found first (milky radiator, fluids mixed) and the coolant flush is only one step of that repair, the category is F (the flush did not cause or sell anything); a later transmission failure is not "a problem after a flush".
R3 A flush mentioned only to say it would not fix the fault is N (no coolant service on this vehicle).
R4 A radiator or other part replaced with new coolant, with no flush/change/drain-and-fill stated, is N.
R5 A flush or fill listed inside a larger service visit or repair list whose story is about something else (recall dispute, oil cap, warranty) is U; listed as "maintenance completed" with no problem tied to it is R.
R6 A flush done (and paid, or by a mechanic) as the remedy for a stated fault is D even if a shop first recommended it or first found bad fluid; a flush done at a visit for another reason where the shop found low or bad coolant is F.
R7 A flush only quoted (not done) in a list of repairs is S.
R8 An oil-side "engine flush" is not a coolant service: N.
R9 Flags: where the two sortings differ on shop_pushed or returned, the flag counts as yes only when both said yes (counts are therefore "at least"). Amounts come from the separate amounts rule.
Added after the added complaints (35 disagreements, read in full):
R10 Same as R2 for the added complaints: contaminated fluids found (transmission fluid, oil, sludge) and the system flushed as a step of the repair is F, also when a transmission fault shows up later.
R11 A flush done once or repeatedly as the remedy for a stated fault (oil in coolant, gunk, sludge, no heat) is D, also when it did not work; coolant flushes listed as ordinary maintenance that did not prevent a fault are R.
R12 A flush or coolant service listed inside a larger repair or oil-consumption test visit whose story is something else, with no problem said to begin right after it, is U.
R13 If the text says a new problem began soon after a visit that included a coolant flush or change, the category is P even when the visit had many other services; the article says "after a visit that included", not "caused by".
R14 A flush recommended or said to be needed at a visit that was about something else is S; a flush mentioned only as not possible or not worthwhile is N.

POOL HISTORY
First search: phrase search of the complaint text (flush within three words of coolant, antifreeze, cooling system or radiator fluid; change, exchange, service, replacement or interval after coolant; drain-and-fill; wrong coolant): 246 complaints. Second search: a separate search of the whole file with other word forms and phrasings (flushed, flushing, cooling system service, radiator service, coolant exchange, misspellings, heater-core flush), each candidate read: 359 added. Total 605.