RootCause Mechanic — the evidence-based mechanic helper
RootCause Mechanic

RootCause Mechanic

The evidence-based mechanic helper.

"I just got quoted $3,800." Before you sign that estimate — get a second opinion built the way a good diagnostician actually works: evidence first, verdict last, and an honest list of what your problem isn't.

Then print the case file and hand it to your mechanic — you're paying for the fix, not the guessing.

$3,900
repairs feared (F-150)
$684.90
actual fix, dealer-confirmed
$6,800 → $0
Kia engine, covered by recall
2 cases
try both in the demo

How it works

The same loop a great diagnostician runs — never guess-and-replace.

1 · Evidence

Build the case file

Repair paperwork, trouble codes, photos, sounds, drive data. What already exists decides most cases.

2 · Hypotheses

Rank the suspects

Honest probabilities from your vehicle's documented failure history — not generic internet guesses.

3 · The cheap test

Discriminate for dollars

The single cheapest question, photo, or driveway test that separates the leading suspects.

4 · Verdict

What it is — and isn't

A ranked verdict, the don't-buy list, and a case file you can print for your mechanic.

Try it — two real cases

Open the Kia and work a case yourself, or replay the documented F-150 case to see how it ends.

Guide tips
9:41RootCause◔ 87%
RootCause
The evidence-based mechanic helper
2013 Kia Optima EX
2.4L GDI (Theta II)  ·  103,410 mi
Pack: Hyundai/Kia Theta II Try it yourself
Open a case ›
2015 Ford F-150 · “the truck”
5.0L Coyote V8  ·  214,864 mi
Pack: Ford Coyote 5.0 Documented case
Replay this case ›

Case history stays alive while a vehicle is active. Lapsed vehicles go read-only for 90 days with export, then are deleted.

New case

What's happening

Build the case file

0 items

Before anyone theorizes, RootCause collects what already exists.

Case file so far

Consult

Working hypotheses

Verdict

RootCause never directs work on brake hydraulics, SRS/airbags, or pressurized fuel — those hand off to a shop, every time.

Account

sample
📷
Capturing…
💡 Guide

Why it's different

Plenty of apps read codes. None of them keep a case file, weigh evidence honestly, tell you what not to buy, or hand you a printout for the shop.

A case file, not a chat

Every answer, photo, and test result accumulates per-vehicle. The verdict cites its evidence — and keeps getting smarter about your exact vehicle.

The don't-buy list

The most valuable sentence in a diagnosis is "it's not the head gasket." Every verdict names the expensive repairs the evidence argues against.

Print for the shop

Walk in with the diagnostic already done. You pay for the fix, not the guessing hours — and the printout is your defense against the upsell.

Launching on iPhone

Per-vehicle pricing, no subscription surprise: your case history stays alive while your vehicle is active.

Get notified at launch